Can't speak to US Cellular, but when you see the ads for Verizon and for AT&T, note the details in what they say - AT&T claims to reach more people and Verizon more of the country (or messages similar to this). Seems to us, from our coverage and those some friends have had, that AT&T seems to concentrate on more big population centers and Verizon is much better in the less-populated "open spaces." There are still hiccups with any of the services, but in general, if you plan to spend much time visiting less-populated areas of the U.S., Verizon would be a good bet.