If you have Sprint unlimited plan it gets free roaming, including data. It pretty much works everywhere, except for places nothing works.
The best coverage I have ever had was from Tracfone. Out in the middle of no where and no one elses phone could make a call and I got through. But of course you get the bottom of the barrel for phones from them. I have Straightalk now. $45 a month unlimited everything. You dont get quite as much coverage for internet in really rural areas, but that just means that you dont get to play your games in the middle of Montana or Wyoming. Almost everywhere else in the country coverage is great. And Straightalk just came out with service for i-Phone 4 & 5. Phone is expensive but plan is still $45 a month.
Before Straight Talk I was on the Sprint contract, 2 phones, $85/mo. Then when I moved back to TN it didn't work. I like the $30/45 plans much better. Update on my new ST phone purchase I was bragging on CDMA (Verizon) but they sent me a GSM (ATT) with a SIM card. To my surprise I have a full signal at the house. The thing about cell service is it's still a growing business and antenna's are going up everyday.
Page Plus uses Verizon's PREPAID network. Not a significant difference, but there is a difference nonetheless. For example, if you run up or down I-81, on P+, you will go into roaming (and pay extra) from the PA/MD line south to the WV/VA line. With a Verizon contract, you would maintain coverage the entire way. You are correct about it being much cheaper and can walk away at any time with no early termination fees. I personally use a Motorola D2G and pay $36.75 out-the-door for Unlimited Talk & Text with great customer service (Kitty Wireless w/Kitty Club). I can also change phones as many times as I want to (ie, Motorola D2G this week, Motorola D3 next week, Casio Commando the next day) and am not charged anything for that.
http://newsroom.t-mobile.com/articles/t-mobile-ATT-roaming-agreement Added AT&T to it's roaming agreements with Cingular and Edge Wireless. There is no roaming agreement with Verizon as the Verizon network runs on a different technology that is not compatible with T-Mobile phones.