T Mobile...
Hey there,
I've been using T Mobile (formerly Voicestream) for a little over a year now and have been happy with my service. As far as coverage goes, I haven't had any real problems with them. Way up in the UP of Michigan and Roanoke are the only places that I've had no service, everywhere else was fine. I fly mainly in the Midwest and Eastern US, so I'm not sure what coverage is like out west.
They've got a new nationwide plan right now: no long distance or roaming fees, 600 anytime minutes and free nights and weekends for $40, not bad IMHO.
I hope that was what you were looking for, if not ask more or PM me and I'll do my best to help. See ya!