Re: Utah, Idaho (Driggs) trip advice
I hired a guide to learn the Juan. The fish up in the quality waters eat really small bugs, mostly midges. If you are not going to buy some flies from a shop there, I would tie some red, cream and brown midge imitations in size 24-26. I would also tie some dun CDC emergers and dries in size 22-24. Fish as close as you can to the bottom.
Below the quality waters you can find some bigger fish using wooly buggers or leech patterns. That was fun for me, be careful with the strike. I was fishing 5x, it was that light or no strike.
For sure, stop in at any one of the shops and ask. They will tell you what is catching fish.
Good luck! You're going to have fun!