Many (most?) of the National Parks were designed with "cars" in mind - if you hope to use a Class C as your vehicle, it might be hard to find parking spots in all those wonderful Scenic Turnouts. Either think SMALL with a motorized RV; or go with the trailer that you can leave behind.
Re the thought of a Wrangler with trailer: while sightseeing with a Wrangler with the top off is just about as fun as it gets: it's not a secure vehicle at all, not a great tow vehicle due to the short wheelbase; and they get poor gas mileage - about the same as a full-sized van.
