Repo Man on the Sweetwater
Never heard about Bitter Creek Falls? Hmmmm.
The Snake River Canyon runs are great, although crowded (during business hours) by commercial paddle boats. The 'yaks take turns surfing between 'em, and God help you if you get in their way.
On the lower part of Grey's River (a tributary of the Snake) is a reach of IV-V water. Good idea to get local beta.
There's some steep, bouldery stuff on the Gros Ventre River as it comes out of the mountains. Lots of creeking in the general area of Jackson and around the borders of Yellowstone. West and north of the Tetons are runs on Canyon Creek, Teton River, Bitch Creek (all IV-V), Upper Bitch Creek and Falls River (III-IV). Mucho possibility of wood & strainer hazards.
Closer to Rock Springs is the Sweetwater River. There's an upper reach from the National Forest to Hwy 28 that looks fun & not difficult. (Look out for logs.) With a friend, I floated from south of Hwy. 28 to Sweetwater Station. We took a Pack Cat and an IK. (In a hard boat, a helmet w/facemask would be smart.) Don't bother except at high flows. The canyons are very tight & rocky, with strainers, sweepers, and logjams, and some sporty drops. We scouted constantly and on the second day portaged a slot-falls (below a huge boulder and swirling pool) that had logs wedged in it and some spooky stuff below.
Where it comes out of the canyon there's one large diversion dam that can't be run, and another farther on that we skanked (in the dark). Once you float out into the valley it's 5-6 hrs. of gravelbed meanders, lots of wildlife, hellish mosquitos. We did that by night, day two, and pulled out at 2 am. Hallucinating without drugs.
If– God Forbid— I do it again, I'll plan on three days and two camps.
If you like tense situations and no crowds, it's the ticket.