Roaming is very expensive for cell companies. And they tend to shy away from offering service to those who wont be primarily in their coverage area. Many companies, in fact would refure to offer you service at all. And it is common practice for about half the companies to cut off your service if you roam more then 50% over several months. Now if you will use the majority of your minutes in that other city and in a companies local coverage area they may sell you service.
With that said, one thing I would like to point out is that you are stuck with the limited cell towers in your area. If Sprint and US Cellular are the only local towers around then even if you went back to the other town and signed up with Verizon you would still be roaming exclusively on US Cell and Sprint towers when your at home. You wouldn't even be on Verizon's own network. So the network will be the same either way. The only difference in the equipment will be who's name is written on the phone your using (and of course the phones offered).
Especially in the case of
GSM, even if you signed up for Tmobile or Cingular, when you are around your home town you will will only have Cell1 network coverage available to you.
I would decide on coverage first, then a plan, then a phone. But with that being said I would probably go with USCell or Sprint if those are the better local coverages. If you don't like their phone selection then I would go online to their company websites to see what they offer. You can sometimes save $ by ordering online as well. Also, you can find other phones available on ebay. Just make sure they are branded to your provider. Also, get the
ESN before purchasing and call your prospective provider to make sure the phone is compatable.
If you decide to go with Cell1 you can change phones to any compatable
GSM phone you want, just by changing out the
SIM. Ebay can also be your friend here as well.