If you are not familiar with Utah at all Matt, it is all about
elevation and
latitude. That is what makes it such a diverse state compared to some other western destinations during January.
St. Georgeis a popular cragging destination in January, 20/30 days would be quite pleasant.
Zion, only 40 minutes away, not so much although you can get lucky with a few days here and there.
Moab is higher elevation than Zion, but south facing routes are more exposed and open to the sun than most Zion objectives making it doable, based on weather forecast.
Red Rockswhich is 2 hrs from St. George is easily climbable probably 20/30 days as well in January. A bit warmer than St. George and longer trad routes. We are combining a Moab tower trip with back country ice climbing near Ouray, CO, in January....the flexibility of pitting these two destinations against each other makes it a successful climbing trip no matter the weather. They are 3hrs+ apart. The camp site you want in St. George is Snow Canyon State Park. Zion and Moab will be cold night camping to say the least. I went to Joe's Valley last year for technical ice around Christmas and was disappointed. Pick the brains of the guys above for better ice destinations than that in January. Joes is probably much better in February. Enjoy!