My two favorite routes...Resurrected from earlier posts:
"The answer is very dependent on the weather.
My two favorite routes are the following:
I-15 north from Salt Lake City to Idaho Falls, ID. Hwy 26 east from Idaho Falls to the little town of Swan Valley. From there, north on Hwy 31 (and over a little pass called Pine Creek Pass) to Victor, ID. From there, east on Hwy 22 over Teton Pass to Jackson. This is the most straightforward route, but it does involve the possibility that Teton Pass might be closed. There's a big flashing highway sign just as you leave Swan Valley on Hwy 31 that will let you know if the pass is closed, so watch for that. If the sign says the pass is closed, you can continue east on Hwy 26 to Alpine, WY and then head north on Hwy 89 through the Snake River Canyon and on up to Jackson.
The route I like better is to head east on I-80 from Salt Lake City to Evanston, WY. From there, you go north on Hwy 89 to the intersection with Utah Hwy 30. East on that for about 8 miles and then you intersect US Hwy 30. Go north on that through Cokeville and then watch for an intersection where Hwy 89 goes north and US 30 goes west. Follow 89 north over a little pass called Salt Creek Pass, through Afton and on up to Alpine. From there, you follow 89 through the Snake River Canyon and into Jackson.
The disadvantage with this route is that it's all 2-lane highways once you leave Evanston. If the weather is bad, as in snow or blowing snow, you're a long way from anywhere if you get stuck or whatever.
If the weather's good, I'd take the I-80 to Evanston to Cokeville to Afton to Jackson route. If the weather's bad, I'd go up I-15 to Idaho Falls to Swan Valley to Victor to Jackson route..
As far as speed traps, I pretty much drive 7mph over the stated speed limit and have never ever been stopped. If you fly along much higher than that, you run the risk of getting a ticket almost anywhere along either route."