fwiw, t-mobile is going that route with all of their phones and plans (called "even more plus"). if you sign up with them and have your own phone (or want to pay for the phone upfront), your monthly plan is less money and you have no contract. you can of course still buy subsidized phones through them for the normal monthly rate and a 2-year contract.
Which kinda makes T-Mobile the only real option if you have an unlocked phone. Why spend all that money on the phone if you're still going to be paying to subsidize something you didn't buy? As long as you're happy with the service, of course.
T-Mobile has constantly been coming out on top as of late, (in regards to customer relations/treatment) but they still don't quite have the network though, do they?
TMobile service is great in big cities. When I go home its 1g and Roaming(free). The real nice point is the great prices and excellent customer service. Today I called to see when my upgrade date is and I had a person on the phone and was done in 1 minute.
T-Mobile also has a policy of unlocking subsidized phones at the request of customers in good standing. 90 days? Paid your bills? Just call and ask. Done.
I've used t-mobile since they were called Voicestream. This was in New England, SW Florida, and now DC. Their network doesn't have the penetration of Verizon but I have never had any substantial issues with service. They even recently expanded to provide service in the DC Metro, which was a pleasant surprise.
I have the same plan I've had since the Sidekick II (with modifications for data on newer devices), which I got with a subsidized phone, and then renewed for two years with a subsidized G1. It is about the same as the new "unsubsidized" price for phone+data. If I buy this phone, I will pay about $20 more per month for service and will be locked into paying it for two years. This is still less than the price of the unsubsidized phone, of course, but I am still kinda annoyed that phone service keeps getting more expensive and only gradually getting faster and more widespread, despite all other kinds of tech getting cheaper and faster.