cell phone coverage

I live (73521) 50 miles away from another city (73501) that has a lot of cell phone providers. Here we only have three, US Cellular, Sprint, and CellularOne (quality in that order). In the other city, there is Cingular, T-Mobile, Verizon, and more. The phones with US Cellular, are subpar for me. I have done some researching and have come down to T-Mobile (top pick) and Cingular. I called both the 800 numbers and the reps there say, we haven't made it there yet, and the whole spill. I could'nt get a hold of the local Tmo rep, but visited the cingular store and they said I would be able to get GSM coverage. I am wanting a nice phone, with a national plan. Would coverage matter? The tmobile map online shows my zip being in the tmobile roaming, and cingular has orange at least 100 miles around me. Am I just screw-ed, or can I actually have coverage? Can any cell phone people help me out on this? I want to make sure I get my info straight.

-Nate