Vinn, the rules about digital TDMA phones is rapidly changing in the mountains. Here in CA, The TDMA and GSM networks have been operating side by side with almost all TDMA in the mountains. Over the past 2-years (since SBC bought AT&T), digital is being phased out with pretty good coverage on the GSM network. Coverage is about equal for both types now in the foothills and Tahoe area, with GSM being clearly superior in the city and along interstate routes.
By the way, you can get GSM phones with 2 to 4 frequency capability (dual, tri and quad mode). Its not generosity on the part of the mobile carriers either. They charge a fortune for internet data transfers, picture transmission and all those features you can download on the GSM network. If someone is buying a phone today it would be pretty foolish to buy the old TDMA network stuff that is being phased out. My pick for a phone is the Motorola MPx220 because it syncs with outlook and can do function as a PDA and camera.
For Sacramento, Verizon, Sprint and Cingular and even Nextel have excellent coverage, but in the mountains, Cingular currently has the best coverage. Nextel has the worst foothill and mountain coverage in my experience, but in town has that cool radio feature.