I live in Omaha NE, Sprint still hasn't turned on their 4G LTE. Verizon's had theirs for ages, but I don't want to worry about overage fees. I always go over 2gb per month. Unlimited data is one of my requirements for a carrier.
Sprint likes to throw around a map of all the places about to have 4G, but they never want to get into tentative dates.
T-Mobile isn't in this area or I'd jump ship. Unlimited data and 4G LTE. I even like Carly Foulkes.
As for the tethering - if you're willing to root your phone there are plenty of Android ROMs that will allow you to tether. I have a ROM called "Blu Cuban" on my Galaxy S2 based Ice Cream Sandwich. I tether all the time and it's never shown up on my phone bill. Check out xda-developers.com If you've never rooted your phone before there's a million videos on youtube to show you how.