Rock Band 3

Pretty much exactly what it says on the tin. Impossible to do by yourself though (I think), so getting band mates is essential. Have some local players with you, or look on Xbox Live. It seems that the maximum number of players you can have at a time is four (that count towards your score as All-instruments mode wont count vocals). The harder the song, the longer the song, and the harder difficulties you can play, and the better you can coordinate overdrive the higher you can possibly score. See scoring system at the bottom.

You can use any song you want, but you must not fail out of it to get the achievement.

For the sake of curiosity I got this with an Expert Drums, Vocals, Guitar and an Easy Keys player on "Smoke on the Water". Although one of the guys online said he already got this with a full Hard band on "Llama".

The following are the longest songs available on RB3 as downloadable songs. These will likely help you get it even if you play at a lower difficulty than Expert:
"The Who Super Bowl S-mashup" by The Who
"Jailbreak" (Live) by AC/DC (from AC/DC Live)
"The Camera Eye" by Rush
"I Heard it Through the Grapevine" by Creedence Clearwater Revival
"...And Justice For All" by Metallica
"Green Grass and High Tides" by The Outlaws (from Rock Band 1)
"Let There Be Rock" (Live) - AC/DC (from AC/DC Live)
"Homecoming" - Green Day (from Green Day)
"Jesus of Suburbia" - Green Day (from Green Day)
"High Voltage" (Live) - AC/DC (from AC/DC Live)
"Descend into the Eternal Pits of Possession" by The Project Hate MCMXCIX (from Rock Band Network)
"I MAED A GAM3 W1TH Z0MB1ES 1NIT!!1!" by James Silva (from Rock Band Network)

The 'goal' is situated in Rock Band Mastery - Score - Millionaire Club

Scoring system:
Note streak:
10 - x2 (1 phrase)
20 - x3 (2 phrases)
30 - x4 (3 phrases)
40 - x5 (Bass and Pro-Bass only)
50 - x6 (Bass and Pro-Bass only)

Harmonies/Vocals (Each Awesome phrase on difficulties):
Easy: 200 (20 for each harmony part)
Medium: 400 (40 for each harmony part)
Hard: 800 (80 for each harmony part)
Expert: 1000 (100 for each harmony part)

Guitar/Bass/Keys:
25 points a note. Chords are 25 times the number of notes in the chord but only counts as one note to the streak.
Pro is the same but at 60 points a note.

Drums:
25 points a note. Two notes played together are separate notes for the streak.
Pro is 30 points a note, except in the case where if you are supposed to play a cymbal, and you haven't selected it in settings as a cymbal you choose to play (so it would be charted on the track as a "normal" note) then those are 25 points.
I.E. If you want a maximum score on Pro Drums, you need to play with all three cymbals.

Bonuses
For Big Rock Endings try and play randomly and as fast as possible. I noticed that for Guitar, Bass and (Pro) Keys that if you continuously play the same notebutton over and over again the score doesn't go wildly high as it would as if you were playing different notes. Try playing Glissandos if you are on Keys or have Solo Buttons on the guitar.
This isn't so much of a problem for Drums and Pro Guitar/Bass. Just keep hitting or strumming away.
Just be sure to nail the final notes!

For tambourine sections on just keep tapping away on the Microphone or the A button on the controller. The points for tambourine sections are only given as a bonus at the end of the section rather than points for every note. The score is based on how many notes you had to hit and how many you did hit. It is similar with Guitar and Drum solos, but the bonus is on top of the normal note scoring. For Drum solos you do not get Drum fills or any chances to activate overdrive, be careful.

Overdrive gives the band a 2x multiplier for the band from each instrument that activates it.

This achievement is Easiest to obtain by playing RB's Free song "Rock Band Network Megamix 01"

Instruments:
Guitar-Hard/Expert
Bass-Hard/Expert
Drums-Hard/Expert(If you end up playing expert drums,The last song that comes up has tricky bass pedals to hit.)
Vocal-Medium(vocals doesn't really need to get a high score)
This song is 10mins Long.Enough time to get a lot of points.

Or you can also try If you more of an expert player:

"Free Bird"
Guitar-Hard/Expert
Bass-Hard/Expert
Drum-Hard/Expert
Vocal-Hard
Also long enough to score points.

"Killing Loneliness"
Band All on Expert.Wouldn't recommend this song unless you're going to at least get 97-100% with all 4 instruments.

"Yoshimi Battles The Pink Robots Pt.1"
Guitar-Hard/Expert
Bass-Medium/Hard
Drums-Medium/Hard/Expert
Vocals-Hard/Expert

RB1 Export: "Welcome Home"
With 3 players scored 1.1M
Guitar-Expert 100%
Drums-Expert 98%
Vocals-Hard 99%
Or with a Band:
Guitar-Expert
Bass-Medium
Drums-Hard/Expert
Vocals-Hard

"(Don't Fear)The Reaper"
Guitar-Hard/Expert
Bass-Medium
Drums-Hard/Expert
Vocal-Medium/Hard

I would also like to say that this achievement is possible with only two people. So if you have the AC/DC tracks play High Voltage(live) with a guitarist and a drummer. Unfortunately you both have to be on expert. But you do not have to play perfect. Playing guitar I got 96% notes hit (and failed out on the solo) and my buddy got 98% on drums and we easily hit the 1,000,000 mark. You just have to time your overdrive activations right. I know there are easier ways, but I was just adding that this is possible with only 2 people. Hope this helps.

I got this solo on 'The Look' by Roxette playing Pro Bass on expert (pretty simple bass line) while doing vocals on expert (not a very tough vocal line).

You can get this achievement playing two songs included on the disc.

I played with two people, with the following configuration:

Music - "Plush"

Bass - Expert - 99%
Pro Drums - Hard - 99%
Guitar - Expert - 99%

Total points: + / - 1.050.000, I forgot to write down the correct value, but increased from 1 million, sure!

"OR"

Music - "Free Bird"

Bass - Expert - 92%
Pro Drums - Hard - 99%
Guitar - Expert - 94%

Total Points: 1,184,806

Sorry for bad English.

"Captain Jack" by Billy Joel

MEDIUM GUITAR (me)
HARD PRO KEYS (someone I found on DLCquickplay.com who prefers to play hard/expert pro keys)

My friend and I were able to end up with a score of 1,702,559!

Download links:
"Captain Jack" by Billy Joel (single)
OR
Billy Joel The Hits: Rock Band Edition (includes "Captain Jack" and 11 other hit songs by Billy Joel)

I got a million on Promise Land and Freebird.

Expert Mode with Guitar Bass Mic and Drums. Wasn't really that bad as I am a Expert Bass player.

Feel free to invite me if you need a Bass player

For anyone with only 3 people like myself, I just got this with The Camera Eye by Rush on expert drums 97% (450k) expert guitar 94% (259k) and expert vocals 97% (108k). All 3 of us got 1,091,938 points (with an 18 month old running around messing up my multiplier!)

Me and my friend got this on And Justice for All - Metallica. Me on Expert Guitar and him on Expert Drums. We both got about 98% and we got about 1.1 Million so it's definitely possible with two people.

If you have exported rockband 2 you can easily do it on PDA with Drums, Bass and Guitar on expert hitting about 98% each but to be safe its best to have someone sing to, If you have the chevo on RB2 try to do what you did on there.

If you play RB3 online and manage to hook up a band with expert pro drummer, expert guitar, and expert bass (which seemed to be a very common combination when I won this), this achievement is not too difficult to get (i.e. the three of us played 4 songs and scored over 1mil on three of them). You just have to score in the upper 90's on all three to win it.

Very easy with "Give it away" from Red Hot Chilli Peppers.

I did it with a Full Band and got 1.140.000 Points.

Vocals - Expert (Vocals alone can get around 350.000 Points without Overpower, 99% or 100%)
Bass,Guitar, Drums - Medium or Hard

On Vocals wait for the End of the Overpower-Segments to start Overpower.
The other Instruments wait for the Vocals to start Overpower for a massive multiplier.

Can be done easily with 2 people if you have exported 'Jesus of Suburbia' from Green Day Rock Band. It is a long, relatively easy song. With me on Expert Vocals and Hard Bass,and a friend on Expert Guitar we scored over 1.6 million, so you don't have to be anywhere near perfect to top 1 mil (I screwed up plenty on bass while trying to sing at the same time)!. You might try one or even 2 of the instruments on a lower difficulty if you can't manage 1 mil with this combination.

The only other advice I can give - and this goes for ANY song and ANY instrument combination - use your overdrive wisely! Launch it on all instruments at the same time (even if it is a quiet vocals part!). Using the above example, with 3 instruments, it will give you a 6x band multiplier. That is effectively 24x for your guitarist and 36x for the bassist if you are in a groove. Your score skyrockets during these moments.

If all you have is rockband3 and no other rocknands then what your going to want to do is if you do not have the rockband network megamix 1 your going to want to get it. It is a free song. It is about ten minutes long. The song on the vocals is not to bad if you have a decent vocalist. Guitar on expert there is one tricky solo that lasts about half way through maybe a little more where if you aren't amazing your going to want to save some star power. Bass is not to bad for this song much easier then the guitar. The drums are a little challenging but not to bad just a lot of different beats since there is about ten songs in one on this. When I got this achievement I was on expert someone else was on expert bass, then hard drums and medium vocals. We did fairly well we averaged all together about a 93 percent or so and got 1.1 million. Hope that helps!