Adamis:
“...6. The drive from Grand Canyon to Grand Tetons looks to be ~675 miles. This we will need to break up into a least 2 days. Split in half we would need to stop on the southern end of Salt Lake City. Is there anywhere of note to stop for a night in this area?...”
We did a part time winter in Mesquite, NV, and usually did the 7 hr drive in a day. We decided to break it up, last trip home, because we were towing our new 5er for the first time.
The KOA at Fillmore, UT, was a great stop and we’ll stay there again. Easy off I-15, and near a Maverick with easy access RV pumps with lots of room.
Have fun and safe travels!