Verizon has, hands down, the most complete coverage in Iowa. We are through them w/ 50+ phones and happy--work all over the state.
Make sure to tell them what industry or organizations you are part of, as homebuilders, etc. get a discount. The beauty of this is that if you work for this business you can then sign up family under your name (just have to prove you work there) and get the same discount. Win/win for the business and your family, as you get the discount and Verizon counts that phone as part of your group, giving you more buying power/potentially larger discounts. I know a lot of ISU people (and possibly still students) have done this.