32GB SD card:
1080p (30 fps): 4h 21m
960p (30 fps): 5h 26m
720p (60 fps): 4h 21
720p (30 fps): 8h 09m
WVGA (60 fps): 8h 09m
I'm going with 720@60fps. I reckon getting the higher frame-rate is better for this sort of thing... also means I can slow parts of the video down in post-processing for funky effects
But you only get 2.5 hrs of battery so that's really the limiting factor...