I experienced similar issues when I first got the phone. Do a search and you will find many ways to increase battery life.
But my experience was to load the power control widget that comes with the phone. Turn off everything when you are not using it. The main thing is to turn off sync. Web browsing kills battery the most... and syncing every 2 minutes is a sure way to kill your battery within 5 hours.
Without sync, gps, wireless, and bluetooth on, I can send a few hundred messages, talk for 1-2 hours, and browse the web for 30 min and I can make it through till the end of the day. People will say you can leave GPS, wireless and bluetooth on and it will not change consumption as long as software programs are not actively running that would utilize those services.
If you try these steps and it still doesn't work, get a blackberry tour. Those things last forever.
Hope this helps.
You've really had problems keeping sync on?
I've never had a problem keeping sync on. Heck, I don't think I've ever turned if off on my phone. I've got my email accounts to sync every 5 minutes, Facebook every 15, and any other little things (not many) as quickly as possible. I've never had a problem with battery life.
Granted, I don't text, but I typically leave for my classes an hour early to get a good seat, so I sit there and listen to music and browse the web. I turn on 100% brightness while walking outside, otherwise I can't see a thing when changing songs. Inside, I turn it down to 0% -- no need for any additional lighting. I browse the web for a good hour-and-a-half to two hours daily,
if not more. This is on 3G too, even though I've probably got faster wi-fi in these locations that I'm browsing. 3G connectivity is still a novelty for me. I came from a dumb phone, and still remember quite well the giant brick cell phones that my parents had years ago. Just thinking about this getting me giddy, but it's great to know that you can browse the web over a cell phone connection. That's amazing. Anyways, I don't come anywhere near the 5 gig non-existent limit every month, so I feel like I might as well browse on 3G whenever I can when time is not an issue. Get my money's worth.
I keep bluetooth, GPS, and wi-fi turned off, and have widgets for those controls on my home screen. No need to keep them running. Whether or not they're actually battery drainers, I don't know. But I know I hate the clutter of a million icons in my status bar.

Anyways, I have sync running 24/7.
I generally don't make many phone calls during the day. Most days I don't make any calls. I know that's a huge power drainer though.
Still, I can't see why you've had such a problem with
sync, of all things. I can typically go through an entire day without charging (12 hours off the charger, give or take) and end up with around 50% battery left. :|