I also agree with Padeye and Geoduck. Write down those places where you MUST have coverage. Take one of the prospective carrier’s phones to those places to see if you can make calls there. While coverage does change over time, the carrier can likely fix coverage that it used to have, but the carrier will not be motivated to add coverage that it never had. (Even the best carrier in town has dead spots and you don’t want to find out later that your house was one of those spots.)
WLNP (Wireless Local Number Portability)
see this link
It is coming on 24 Nov 03. The FCC has suggested that this move of your phone number from one carrier to another take place in 3 hours, but it appears to have mandated that it take place within 6 months after you request it. It is only mandated for the top 100 MSA’s in November, so won’t be required/available everywhere. (However, the carrier might accommodate you in the rural areas.) You can only keep your number in the same local calling area, so you can’t take your phone number from Houston to Dallas. Pricing is unknown at this point.
One more thought: These sites are great resources, but don’t assume that they have captured anywhere near the number of dead spots. Your experience may even be dramatically different than those wireless users across the street, so one can’t expect these pages to be able to succinctly capture all the possible holes. Having said that, perusing these sites (and others) can give you much better insight into any problems that you are likely to encounter.