Also - one last nice thing about Android phones -- you can swap the batteries if need be. Granted, this isn't even a concern 85% of the time and in normal day to day life - but it's a lifesaver those few times I've needed it. When traveling, and knowing I may be without access to a charger for a day or more, it's certainly comforting knowing I can swap out battery packs as needed and have uninterrupted access to my phone and email.
Forget about powering down, limiting usage, or "conserving" your battery... just change batteries!