I have the extended battery as well, but my battery life on CM7 (and Liberty GB) has been somewhat disappointing compared to when I was on Fission and Liberty FroYo.
I'm getting way more than I need with CM7. I'm on auto brightness, no OC, generally stock settings on everything else. Leaving wifi on, no GPS.
I was trying to calibrate my battery which requires charging to 100, hitting calibrate, running down to 0%, then recharging. I tried to run it down to 0 over 24 hours. Took be about 30 hours total. And I was doing all sorts of crap. Kept my phone on with music full blast while swimming. Did a ton of browsing. Left my GPS on for hours. Ran the flashlight Torch app. All sorts of crap.
It still took 30+ hours from 100 to 0. I slept a whole night after running it down as much as I could the day before and it didn't turn off until I was at the theater the next day watching a movie.
TL;DR: maybe you guys should calibrate, because my battery lasts a long ass time.