Another vote for the SLC KOA. Decent sites, with some very nice ones for bigger rigs, and centrally located, with relatively easy access to I-215, I-15 and of course downtown. I believe there is a Trax line right by the CG too (the commuter rail line in the city). Not too many other choices in this area. Provo would probably be fine but in the morning traffic going into SLC can be pretty slow & busy.