Given a choice I would go through Vegas. Love the Oasis. Next stop is a lovely little KOA in Beaver. Small, clean, friendly, nice playground, and very small townish. We've made it our midway stop a few times. In Salt Lake City we really like the SLC KOA. Central to town, paved large campground great for bikes, nice hiking trail along the river, about a 1/2mile from the fairgrounds, just in case something is at fair. The tour of the Mormon Central Square is lovely, (we're not Mormon) but the kids still enjoyed the history of the West. If you have time and stop at Salt Lake City, do take a car out to Antelope Island. We didn't get there until our 3rd trip through the city, it is really hard to find the entrance road. The Island contains the country's largest herd of buffalo, then there is the historic western ranch at the end of the island. Lots of birds. It was a fun day.
Happy Trails.
