I have a 4S on AT&T (my account), and no longer bound by any contracts. I want to buy the iPhone 6 and at the same time move my number over to Verizon (and go on my wife's account) so that maybe we save a few $ on a family plan. And if possible, I'd like to sell my 4S to get some kind of credit or cash. Any suggestions? Should this be done in-person, or try my luck online at the Apple or Verizon websites? Or order online and pick-up in store? Thanks.