Big, big fan of St George, UT. Close to Zion, one many other sites in southern UT. We have been there the last two winters.
Check out Snow Canyon, State Park, in St George. They have a handful of hookup sites, its the off season, so they usually have plenty of room. St George is a nice town, plenty to do there. Several nice hikes in Snow Canyon SP by the way.
We gave winter in FL a try, then AZ. Finally we realized St George was the place for us (in the winter, hotter than heck in the summer!). Yes, the weather is not as good as FL or AZ. But its better than here.
We were even able to come back via I-40, went diagonally through NE AZ through Jacob's Lake. Snow piled high on both sides of the road, but the pavement was dry.
Lower elevation than the 4 corners area, not as warm as southern AZ of course. St George is in the desert, so its usually dry.
Watchman Campground in Zion also has electric hookups. A little cooler than St George.
Be sure to visit Kanab, and sign up for the lottery to hike the Wave! We were fortunate and got drawn to hike in February 2020.
The biggest challenge with St George is getting there. Two years ago, we had to cross the USA on I-10, all the way to Phoenix, before we worked our way north through Las Vegas (some backtracking). Then in 2020, we were able to go I-70 all the way, VERY UNUSUAL!
You really have to watch the weather very carefully, and be open to changing your route. We stayed in Golden, CO a couple of extra days waiting for conditions to improve on I-70. Colorado DOT has cameras all over I-70, with real time road conditions and video. I would definitely NOT plan on taking I-70. I-40 may be OK, may not. It changes rapidly. Be FLEXIBLE on routing! Give yourself extra time to adjust your route.
The west is ALL about elevation. High elevation = cold weather, possible snow, etc.
Here's the "trick" to getting drawn in the lottery to hike the Wave. First, they draw every day, in the winter the drawings are Monday through Friday. The drawings are for the next day, so Friday's drawing is for Saturday, Sunday and Monday (triples your chances!), But wait, it gets better! Pick a Friday before a Federal Holiday, like MLK birthday, and the drawing is for FOUR days: Saturday, Sunday, Monday and Tuesday. Only ten hikers are drawn per day. People from all over the world travel to do this hike. And if one entry is for 6 people, and another is for 4, then all ten spots are gone.