If I had 3 nites I would come in through Grand Tetons staying at Gros Ventre CG where you can almost always get a site. Spend the rest of the arrival day in the Tetons and part of the next day and then drive to West Yellowstone or Gardiner and stay in a commercial CG. Probably can't get" in the park" reservations this late but get as close to Lamar Valley as possible and make a long (daylight to dark)day your last day in Lamar Valley area to see wildlife and ride up toward Beartooth Pass to see the great scenery and eat lunch in the little sidewalk cafe in Cooke City. Research the route from Tetons north to see where road construction is lightest on the YNP website. It will be about a 4 - 6 hr drive from GT to north YNP.Use your toad as much as possible to be able to park at parking lots or pull off the road for bear or bison jams. If you really want to see critters there are some really good guides that can help you in Gardiner area. Price maybe about $400 day. Cara McGarry (check spelling) was super nice and knowledgeable and showed us much more than we would have seen on our own even though we have our own scopes and binocs and have been there a few times. We have seen the geothermal sites several times but like the critters better. You could go by Old Faithful and through a lot of the geothermal area on the trip north from GT. Try to add another day and make the GT part of the trip a full day on the second day.. Research both parks and try to have ideas as to what you want to see.
