Sounds like a great trip
Probably check websites that offer the fishing gigs and see if they have recommendations to give you with some tips. But I think if it were me I’d be taking My 7 and 8 wt fly rods. I think you’ll encounter windy conditions, and tossing big streamer flies or weighted nymphs, both which can be tough to cast with lighter weight rods even if the winds don’t whip up. If you have 9 footers, great, but I’d use nothing less than an 8 1/2 foot. In my 8 weight rod tube I can put two rods in it by putting the rod handles opposite each other in the tube, then you get to take both.
As far as flies, again check on local websites for the area or do tackle shop search for the area and see if they have stream reports and what’s working….otherwise, just cough up some $$ and buy when you get there. I seem to always buy some when I get to the location especially if I’m pumping them for the what and where information.
Have an awesome trip. I’m heading out to Idaho to either the Salmon River or Snake river country. Can’t wait!