You might wish to check with T-Mobile.. In a recent poll of Cell Phone customers they placed 2nd (Verizon is number 1) edging out AT&T at 3rd place and all the others below that.
T-Mobile is yammering about "No contracts, No contracts" all over the media. And they do allow tethering at least on some phones and plans.. IF I were not in a park with Wi-FI.. This message would prove it.
(I am in a park with variable Wi-Fi, Park full, crappy, park is a long way from full, Wifi antenna is on a short tower.. If the short tower falls over.. Well.. Let's just say I might suffer damage (Ok, not that close but Well, it is DIRECTLY across the drive.)