After having spent a total of 8 days in Grand Teton and Yellowstone National Parks, we took a short break in Island Park, ID, When exiting YNP through the west entrance you immediately pass through the town of West Yellowstone, Montana. This visit to Montana doesn’t last long, however, since Highway 20 turns south and you enter Idaho and very shortly come to Island Park.
There’s not really much of a town but there is a nearby lake and plenty of fishing and hunting opportunities. We parked for 3 nights at the Sawtelle Mountain Resort where we once again had full hookups and WiFi service. This gave us some time to catch up on email, blog posts, organize photos, do some laundry and clean the motorhome inside and out. It was a pleasant and productive stopover.
Next up: Idaho Falls, ID
Second Act 
You should consider going north to Glacier National Park, it is spectacular. We went there a few months ago: https://webetripping.wordpress.com/2015/07/23/fleeing-the-glacier-national-park-glacier-fire/