In terms of Silverton/Telluride, Silverton is more rustic, "downtown" is filled with souvenir shops for all the tourists that come by train, and more authentic to its mining town roots. Telluride is more glitzy, high end restaurants, real estate offices, and art galleries. Both are beautiful. I don't know what activities you have in mind. There are more easier 4x4 trails around Silverton, those around Telluride are generally more difficult IMHO.
I note that you are from SC. If you have limited experience towing in the mountains, many will advise not taking US 550 from Ouray to Silverton. Coming in from the south (Durango to Silverton), has less exposure. Another option would be to camp in Ouray and commute to both Telluride and Silverton. The route you mentioned from Moab to CO 145 is fine. There is one short (one mile) segment that goes downhill through a couple of switchbacks. Watch the recommended speeds and use your transmission to keep your speed in check.
