You can go to the Arizona Strip from St George. There's a lot to see out there, Little Black Mtn isn't far and is a nice Petroglyph site. From there you can access Warner Valley and visit Ft Pierce and a Dino track site. You could really make a day of it and head out to Toroweap, it's a long ride but fun, go out from St George and back from Fredonia, AZ.
If you want to wheel, check out Red Mountain, lots of sand and slick rock. Register at:
, some of them might be going out there or someplace cool.