I have a Nextel. There'* good and bad about it. Like you Gordy I had a bad impression with Nextel'* billing. I was charged for two phones and two service contracts. It took FOUR FREEKING MONTHS before everything got cleared up.
That left a huge negative impression with me, I don't think the billing departments had good communication.
As for their batteries lasting longer?
That depends on brand. I had a Motorola i95cl and the battery discharged for no reason. Dealing with Motorola was easier than dealing with Nextel'* billing snafu. The reception seems better than the local cell provider I had before. Nextel won't bump your phone to analog since their tower use a different technology than other cell companies. I also really like the Direct Connect feature, that saves a ton of minutes.
I'd suggest finding a phone with a SIM card and USB port.