I am getting ready to upgrade from a Droid 2 to a Droid Razr MAXX, which gives a phenomenal amount of runtime for about the same overall weight. Not that I would run it continually anyway, but still. And it is one of the newer designs with the gorilla glass, kevlar backplate, and stainless steel frame. Not bad since I feel it's important to tote a cellphone anyway.
Update: got the Razr MAXX and it is an excellent tool. I tested the battery life by charging it to 100% then using the phone normally until I got down to 15%. No short charges along the way either.
I got 3 days, 3 hours, 9 minutes. Continuous.
On the trail I'm using
this waterproof case/bag to protect the phone from moisture. So far so good, though I think I should put a small dessicant packet in there for condensation. A hardshell case would provide better mechanical protection but I'm reluctant to put up with the weight and bulk.