There are many examples of different bump crossing methods from that year; do some research and you'll be richly rewarded.
I pulled a couple for you.
2056:
http://youtu.be/DMt1Ju4ZsUo?t=14m31s
8 x 8" pneumatic wheel
254/971:
http://youtu.be/G0Tb4dP2RmA?t=1m43s (254 and 971 used very similar mechanisms to lift the robot a bit before bump crossing)
254: 8 x 4" treaded wheels
971: 6 x 3.5" treaded wheels
(forgive me if I get the diameter wrong, I can never tell whether someone is using 3.5" or 4" wheels. They're all small to me)
971 "Behind the Design Document" that has some additional information:
http://www.fightingpi.org/Resources/...Team%20971.pdf
Also, what do you think defines the "best" bump crossing method? Using large wheels might, with the proper implementation, make for improved bump crossing . . . but there are tradeoffs to using large wheels as well.
For example, if your bump crossing method requires a high ground clearance (likely if you're relying on using large wheels, though that as always depends on implementation), you're raising the CG of your bot. That could be bad for accomplishing other more important strategic goals, such as balancing the bridge (critical for seeding points in 2012).
Just things to consider.