Another vote for T-Mobile
I think it's something like $60 for our two-phone plan, and a total of $80 because we have two additional lines on top of that. I don't know how many minutes we get, because we NEVER go over. Talking to one another is free. Long distance and local are the same rate. Coverage is better than any other service in our area. Customer service is very helpful, but rarely needed. I'm not going anywhere.
Some things to look for:
Coverage: most mobile stores in malls and shopping centers will loan you a non-functioning phone for a day. You can carry it through your daily routine and keep an eye on the signal meter to see where you do and don't have coverage.
Minutes: think about who you'll talk to and for how long before you settle on how many minutes you need each month.
Free phone: mobile phone are way overpriced, but most plans come with a free phone. I like Nokia, which is all T-Mobile uses now, I think. The phone you use really makes a difference: battery life, signal, reception, & ease of use are all important.