My wife and I are on the Verizon network. My wife uses the HTC Droid Incredible and I recently got the Motorola Droid X. I've used a number of other Android smartphones including the HTC Droid Eris, the Motorola Droid, and the HTC Droid Incredible. I'm now using the Droid X as my main smartphone (and I'm selling a couple of smartphones on eBay right now).
The Droid X is a large smartphone, but I don't mind the size given the fact that the device is also really thin. I prefer to use my phone in a vertical (portrait) orientation, so it helps to have a large screen so that I can easily type on the on-screen keyboard. I usually type with one thumb while I'm holding the phone in the same hand. I think I picked up this habit when I was using a Palm Treo. I never developed the habit of typing with two thumbs.
If you like to enter information using two thumbs, go with the Droid 2. You'll have the option of typing on a hardware QWERTY keyboard or using the on-screen keyboard. As for me, I don't do that much typing on my smartphone since I always seem to have a computer nearby.