FWIW,
I try to keep a close watch on various plans as I use my cell phone all the damn time.
Depending on your needs, you can save some money by going with one of the national/regional plans that utilizes the company's network. If you travel frequently to 'BFE' then you might need to go with the entire country plans.
They cost you considerably more, but you get coverage everywhere, although there are many parts that don't get a signal despite apparent coverage.
If you are in a major city and don't travel too far, but still want to call long distance and if you only travel to major cities, I would highly highly recommend the AT&T new GSM plan where you can get 1000 minutes for $40 or UNLIMITED for $100/month. (You also get internet access for additional fees).
I have actually decided to go with this plan plus keep a phone on the AT&T One Rate plan that allows coverage wherever you get a signal. It gives me 1500+ minutes on the phone that goes anywhere, plus unlimited calls on the phone that only now works in big cities..... saves about $500/mo for me!
And if you have any chance to jump on that AT&T GSM plan, the new towers should be going up soon to atleast cover the current AT&T TDMA area, fwiw.
Drop me a private message or email if you want any more info, I try to continually check these things out.