Hey Lawrence,
One issue facing ralliers is that most of our venues are in very rural areas, which have not been the targets for license purchase or construction by the major carriers. Unlike Canada, we do not have just 6 or 8 wireless operators; all of the market licenses can go to anyone, large or small. So our rural rally markets often are served by smaller wireless carriers. Houghton is best covered by Dobson, who I think sells as Callular One in that area. USCellular is best in the Rumford area. There is another smaller regional operator in the Wellsboro area.
Your best bet is to get service with a major carrier who has roaming agreements with the smaller operators in these markets. The best way to figure this out is to look at the major carrier service maps on their websites. Make sure you look at the map that matches the plan you are considering! For US residents, it's best to get one of the flat rate, monthly, nationwide roaming plans, where their roaming charges are taken care of in the regular bill. For someone who is not in-country too often, I am not sure if a flat rate monthly serivce is the best deal.
Verizon Wireless seems to be the most ubiquitous; Cingular would be the other best choice. They both tend to be stronger on one end of the US or the other; VZW is stronger in the eastern half and on the west coast. But again, look at thes service maps.
Make sure you purchase a phone that will work on analog mode. These are often referred to as tri-mode phones, or dual-band, dual-mode phones. Do not purchase a digital only service; make sure you get analog service too. Also, do not get Nextel service; it is fine service, but due to the technology being used only by Nextel, and their different band of operation, you cannot roam with Nextel on anyone else. (That will change eventually when they merge with Sprint PCS.)
FYI to everyone, analog service will be terminated eventually in the US. I think this is about 5 years out. For rural use, GSM will probably be the best replacement; the technology lends itself best to longer distnace coverage as opposed to CDMA. However, CDMA seems to be gaining ground overall; we will have to see which dominates.
Good luck!
Mark B.