It would be nice if there was a certain (edit - as in positively accurate) way to determine which app(s) keep the phone awake when they shouldn't.
My up time is currently at 30 hours, awake time at 1:40, and battery at 70%, probably going on 60% - I don't have the battery life widget installed. I have not taken any battery saving measures, ie. "Enable always-on mobile" is checked as is "Background data". I have my gmail account set up to sync the calendar and contacts, and the HTC mail app set up to grab my gmail via activesync "as they arrive", and IMAP for my Yahoo mail.
But yesterday was a different story. Everything was running fine, with numbers like above, but at some point I did something that caused it to stay awake continuously. As best I can remember, I used bluetooth on the phone, and turned it back off when finished. I listened to Slacker. Also the FM radio and turned it off when finished. bTunes as well, and used "Exit" to leave that app. The grand total time of usage with all music items above was probably 45 minutes. Oh and I also plugged it into the computer so that I could copy some MP3 files to it.
So today I haven't done any of those things and I haven't had any problems. Tomorrow I will start one by one and pay attention to what happens with my awake time. But this could be more difficult to track than by using my method. That's why an app like "spare parts" that is certain to track apps that keep the phone awake would be useful until the bugs are worked out.