One thing that kills my battery, actually, is Google Play Music. I don't use it much, but occasionally listen to music while driving. I have no music stored on the phone, but steam from my synced library online. If I play music and then forget to switch to another media app, play music will decide to "cache" music for me in the background. Apparently I did this yesterday. I hadn't used my phone for an hour this morning after taking it off power and when I first powered on the display and the battery was down to 89%. That's hardly ever happened; the only times it has it was because of play music (maybe 3 times in the past) and once it was constant calendar sync when the calendar data was corrupt. Checking battery stats, sure enough - Play Music had used 67% of the battery (and I was not listening to music.)
I love/hate this app. I may switch to amazon just to see if that app treats battery any better.