According to the 4G map, I'm in the area. However, it's very rare that I get 4G service. In most cases I get roaming service. This never happened while I was with Verizon.
I believe Sprint's trial period is 14 days (sprint.com/etf). If you're within that time then you should be able to return the phones without any issues.
As far as LTE is concerned, you need to be in an area where Sprint offers LTE. Just because your friend on Verizon has the same phone as you and gets an LTE signal, they're still on Verizon so that would have nothing to do with you getting LTE service on Sprint. I would check Sprint's website (or call them) to see if you're in a Sprint LTE area which I don't think you are.
(I hope my post didn't sound rude as that was not my intention.)
Almost since I got the phones. I work in NYC and live in Central Jersey. Apparantly, they are 4G LTE. A coworker of mine has the same phone using Verizon and always gets 4G service in NYC.
Around a week ago, I signed up 4 new smartphones (two Galaxy III and two Iphone 4s). Service is horrible. Never get 4G on our Galaxy III. Phones always go to roaming. Can I return the phones and not be charged early term penaly?