I have an AT&T Nation Plan for $29.99 (200 anytime minutes, 1000 night/weekends). Though I've been getting hit with a 10 cent/text message charge... may add the service for another 2 bucks where I get 25 messages free before they start to hit me with charges.
I may upgrade the phone too, I have a Nokia 5160 I believe, old school compared to what's out there now.
As for service, once I've went national, I've have no issues with unexpected charges and the service isn't too bad (I think the phone being old is what causes some of my drops...)