Spider-Man 3

To be good at these you have to know where the bombs are and how to get there as fast as possible. My first try on all the bomb tours I got gold except for challenges 7 and 8 (the last and hardest tours). The challenges inside the bombs get easier as you play through more tours, I beat all of them in under 2 hours, failing 3 times or so in all. Bronze medal is VERY easy to attain if you can get to the bombs fast enough, disarming the bombs in only mildly challenging.
Challenge 7 is entirely about web-zipping. you'll have to fly through the park as fast as you can and when you have to go over the water, 95% of the time with a decent zip you'll make it over and save a few seconds when trying to reach a bomb. Just be patient, I died twice on this challenge with the in-bomb mini-game timer running out right before I pressed X to disarm the bomb for good. You'll get it eventually.

Challenge 8 is just running up and down between levels of the train station. THESE BOMBS ARE IN THE BEST ORDER THAT I CAN REMEMBER, if they are out of order, post a comment and help everyone else out. It is also helpful to familiarize with how to get to the bombs the in the quickest way possible, because as you are scrambling to get to the next bomb, you may freak out and get turned around---I know I did.

Bomb 1 is easy to get to and from there, go directly under where the bomb is and go in the doors to the right (they are the only open doors I've found in this tour).

Bomb 2 is up in a little alcove near the ceiling.

Bomb 3 is downstairs to the left of where you entered the train station.

Bomb 4 will be on the same level of the entrance to the right in the corner from where you walked in.

Bomb 5 is on the ground floor level of the station but it is hidden under a bridge-like arc making it seem like it is lower by the underground. This is not the case.

Bomb 6 is right next to where bomb 3 was found, downstairs to the left of where you entered Grand Central Station.

Bomb 7 is in between the set of upper train tracks.

Bomb 8 is on the top of the building (on the roof outside). To get to it, exit the middle door that is to the most northern set of doors in relation to your mini-map.

While bombs tours 1-5 were easily bronzed, tours 6, 7 & 8 seem to give people problems in hitting the time goals. Here's a few tips that might help you pass the final three bomb tours.

Tips for disarming bombs quicker: If you've made it up to tour 6, I'm sure you are familiar with how to defuse the bombs. Nonetheless, here's a few things I did to speed up the process...

Always be ready for the bomb sequence.

*RT/LT plates: Hard to mess up - just make sure to do it right.
*Y plate: Spam Y, like you would of course, except try not to be too quick, or too slow. Maintain a fast and steady rhythm. Don't go so fast that you tire yourself out and slow down. Also, you can press Y "too fast" in the sense that while you may have hit Y 10 times, the game only detected 7.
*Bolts: Spin RS with your left index & middle finger while spamming X+A with your right index. Don't wait for which button you'll have to press to take off the bolt (X or A), just make sure to keep hitting X+A and that you're moving the RS properly/smoothy... the bolts will be off shortly.
*Yellow Fluid: Drain both fluids at the same time & simplify it first - hit X or B first AND then, using your right index & middle finger, alternate between A+B & X+Y... super easy.
Guitar Hero: Do this on your first go. If you don't, at least make a point to remember the pattern for the second go. If you keep messing it up... don't ever play Guitar Hero.
Combination: This can be mildly annoying as your brain often presses the wrong buttons or none at all... and the pattern resets and you have to try again. Take a deep breath & really focus on your reaction time for five seconds.
Maze: Don't panic. Find your destination and work your way backwards. It might take you a few seconds to track the path and you will likely restart the maze 1-3x while you do this but knowing the path you have to take is most important and this is the quickest way to figure it out before you blow up. Make sure to always pivot the earlier "nodes" first, use proper timing if the are two "nodes" with the same button that you have to press and make sure you don't miss any because sometimes they like to hide.

*Put your controller on a stable surface during this sequence.

Make sure you utilize your Spidey-sense when you do these tours. While it doesn't make the timer go any slower, it does allow you more reaction time to land your swings/jumps just right or at the very least... not completely terrible.

Tour 6: The bombs on this tour can be easily located and travelled to just make sure to be extra-fast when you move between them. Slingshot yourself around the corners of buildings (make really hard turns to gain speed). Be wary of losing time as you approach the bomb site - eg. let go of LT and stop moving so fast and running off the edge, stop dashing 100 feet when it's 10ft away etc. Make sure you maintain your momentum & speed in this one. If the bomb is on the roof of a building, blocks away and you're on the ground, try and move "up" and "over there" at the same time - doing one AND then another will cost you too much time as you do that over 6 minutes. Conversely, if you're on a rooftop and the bomb is ground-level and blocks away, make sure to utilize gravity and do your best to "fall" all the way to your destination.

Tour 7: Try and get to each bomb between 0:56 and 1:00 - disarm them by around the 20s mark. If you maintain this over the eight or so bombs on this level, a bronze is essentially guaranteed if you also do the following... When you are dashing across/over/through the trees by hitting RT, hit your LT as well and try and time it for right after your web connects to the top of a tree and yanks you but before Spidey lets go of his web. While he is connected for that brief moment (0.5s~), a properly timed LT will give you a really handy speed boost. DO THAT AS MUCH AS POSSIBLE. The bombs are fairly straightforward to get to in this level and after you disarm the last bomb located at the building where you started, you can move on to bomb tour 8.

Side-note: If you can manage a stunt (ex. grab his toes) at the end of that "dash-boost", Spider-man seems launch even further & faster and in a slightly more controlled way. Do this by double-tapping the LT, and, while holding it down the second time, press X/B/Y/A. It's a bit difficult to master this technique but when you are able to pull that move off at your discretion, you can make quick work of the harder trick races.

Tour 8: Once you locate where all the bombs are and you are familiar with Grand Central Station enough to move around inside without getting lost, bronze is easily attained. Make sure to hold down LT while you jump and run your way to the bombs. If you still need more time, use the dash technique I described in bomb tour 7 as you move through the stairwells and hallways to gain you some precious seconds.

Bomb locations (bomb tour 8):
1. Bomb on the side of building - easily spotted.
(Go inside the building via the doors at ground level)
2. Bomb on the right side of the ceiling inside the building. (up on the d-pad comes in handy)
3. Bomb on the platform down the stairs.
4. Bomb in the corner of the main floor.
5. Bomb underneath the arch on the main floor level.
(Jump back up top, don't get lost in this hallway)
6. Bomb on the ramp to subway, just a little further down from bomb #3.
7. Bomb between the subway tracks.
(Leave the building the same way you got in)
8. Bomb on the roof.