Another St George Utah resident here, only moved here in March 2012. Part of what we love is how the area is large enough for a Costco and other big-box stores, but really has small-town qualities all around. Lots of access to the great outdoors (mountains up to 10,000ft for getting away from heat in the suumer). And we're only 2 hours from Las Vegas if we need real big-city stuff. There is a world-class hospital in town.
It was the access to the outdoors that kicked us into buying a TT last year and we visit some of the same places that previously were day trips. But the difference of being there at dawn/dusk/starlight is amazing.
We're now mid-50's and wanted to test-drive the area we hoped would be our retirement home-base while still working. Since you're going truly mobile, you can try more places.
As you gather more details about candidate locations, be sure to key in on politics/taxes/city budgets and the like. Although Utah is becoming more diverse, the dominant religion affects politics in both good and bad ways.