The wife added a stop on the 2018 great american roadtrip

We have stayed at Jim and Mary’s it is a good park. When we went to Yellowstone we stayed in Anacondia and drove through Virginia City with the fiver, not a bad drive and as others have said you can see Virginia City in half a day if you desire. Then continue onto Yellowstone.
Enjoy

There is an RV park in Virginia City if you want to stay right in town. Haven't stayed there, but have seen it. IMHO, it only takes a couple of hours to see all the "tourist sights" in Virginia City, so you may want to just stop, visit, and continue on your way between Glacier NP and West Yellowstone.

There are also a couple of very small, but shady RV oarks in Ennis, if you just want to leave the RV at one of them, drive over to Virginia City, visit for the day, and drive back. That way you could just stay on US 287 to continue your trip. Take a look at RVParkReviews.com for more info on the Ennis RV parks.

I highly recommend stopping at the Earthquake Lake Visitor's Center on US 287 44 miles south of Ennis. In case you don't have a personal memory of the event, Quake Lake was formed by the August 1959 Hebgen Lake Earthquake. A Forest Service campground in the Madison River Canyon was buried by a landslide, killing 21 people and trapping another 300. A geologist I worked with was doing field work nearby and experienced the quake first-hand.

Virginia City - stay in nearby Ennis at Ennis RV park. If you do any fly fishing the area is perfect.

http://www.ennisrv.com/

http://www.rvparkreviews.com/regions/montana/ennis/ennis-rv-village-4477

Here are others in the area:

http://www.rvparkreviews.com/regions/montana/virginia-city

Jim & Mary's in Missoula is nowhere near Virginia City.

Have stayed at Countryside RV in Dillon. Short drive to Bannack and Virginia City If you are coming up from Utah or Idaho but not so much for Yellowstone. Jim & Mary's is a great park but a long way from Virginia City, Yellowstone or Tetons.

X 2 for Jim & Mary’s

Jim & Mary’s Campground. West end of Missoula just off I-90 at MT-93. Neat, clean, quiet, nice people, all utilities, plenty of pull throughs, laundry facilities. We stay there east and west when passing through Montana.