Oh, wait a minute...you only said 89, which makes it unclear. All roads to Jackson utilize US-89 as you have to pick it up at some point, the question is where. Sorry, I responded without having a map in front of me.
I assumed that you were talking about getting to US-89 via US-189 through Kemmerer and US-30, but rethinking this that may not be the case. Just in case you're talking about taking US-89 starting from I-15 at Brigham City there are a few things to know. FYI, on US-89 Logan Canyon, which runs from Logan to Bear Lake at Garden City, is tight, twisty and has a large climb (and descent) just west of Bear Lake. Logan Canyon is slow going. Just east of Brigham City, Sardine Canyon is also a large climb, although at that point US-89 is a wide, fast road that connects the Salt Lake Valley to Cache Valley. One redeeming quality of this route -- despite the lousy road through Logan Canyon -- is that Bear Lake is spectacularly beautiful for a stopover. Its mineral content creates turquoise water that has prompted many visual comparisons to the Caribbean. Renedezvous Beach is a huge state park campground located waterfront at the south end of the lake with full hookups.
Personally I'd go I-80 to Evanston, then north on WY-89 (crosses back into UT and becomes UT-16), then east on UT-30 (which becomes WY-89 as you cross back into Wyoming) to US-30. North on US-30, then turn right onto WY-89 at the state line to pick up US-89 N at Geneva (yeah, lots of 30's and 89's there, hence my addition of the designation for each). If you go that way there's also a Flying J along the way in Cokeville for a fuel stop well after you've left the numerous truck stops of Evanston in the rear-view mirror. The Star Valley (Afton to Thayne) also has all manner of services. Despite all of those route number changes it's pretty much a straight northward shot from Evanston to Jackson. Don't let all of those route number changes fool you.
Another good alternative would be to take I-15 N from SLC to Idaho Falls, then east on US-26 to US-89 in Alpine Jct. By going to Alpine instead of through Victor to Jackson you avoid one minor pass and the major Teton Pass. It's slightly longer but a much easier drive to follow the Snake River than head through Victor and over Teton Pass. If I'm not towing this route is quicker than going through Evanston, but YMMV depending on how fast you're willing to drive with a motorhome and a toad in tow.
One of my favorite places to camp near Jackson is the Crystal Creek Campground in the Gros Ventre Mountains of Bridger-Teton National Forest northeast of town. I've got photos from our visit here:
http://www.firsttracksonline.com/boa...=11049&p=69523 . It's close to town, yet miles away from everyone else along the bubbling waters of the Gros Ventre River. Another spectacularly beautiful choice, but much farther away from town is Granite Creek northeast of Hoback Jct., but that campsite comes with a bonus on-site waterfall and hot spring pool. ;-) Photos from our visit to Granite Creek are here:
http://www.firsttracksonline.com/boa...t=6906&p=35941 . Both are Forest Service primitive campgrounds, there are no hookups at either, and the roads to reach each are graded gravel.
Feel free to backchannel me if you need anything -- I'm in the neighborhood.