Lately I've been engaged in a war with battery life on my phone, having a lot more problems with recent roms.
I've found extremely bad battery drain with any alternate kernals, imos in particular with the exception of the one in thundershed, I also noticed that regardless of the rom both slacker and pandora have been causing my phone to stay awake 100% of the time, after I removed them on the happy trails rom my battery life is now actually very good.
Using spare parts to see apps that are keeping your phone awake and cpu spy to check that the phone is properly going into deep sleep the majority of the time your phone is off helps, if you have no out of control apps the deep sleep in cpu spy should resemble the amount of time the phone has been idle, obviously not 100% there are legitimate background tasks that can wake your phone, checking emails etc, but it should be relatively close.
I've also been looking for alternatives to any apps that display ads as they are normally battery killers.