Which route would you prefer taking? Down through Idaho to Utah? or over Beartooth and into Wyoming? Both have good water, although the Wyoming route may have a bit more. The Idaho/Utah route being more Interstate Highway would be faster from spot to spot.
Personally, I think I would go for the Wyoming route just for the slower pace (wow, I must be getting old!).
Wayne: If you came down the ID/UT route, Hebgen Lake for Gulpers, South Fork of the Snake by Swan Valley (stop at Jimmies in Idaho Falls, buy a few flies and get the skinny on public access points), the Green River above Pinedale, WY by the Warren Bridge (lots of BLM land for river access and free camping), the Green River below Fontenelle Reservoir, below La Barge, WY (again lots of public access and free camping), then hit the Green River below Flaming Gorge Reservoir (Dutch John, UT area, again it is all BLM, pay to camp, and there is a BLM trail from the dam to the first boat takeout at Little Hole, lots of opportunity to spread out and fish without feeling crowded.
If your interested in doing a float together (I have a drift boat) and if the dates work let me know.
If you wanted to go through Yellowstone NP, check their website a few of the rivers were closed earlier in the month due to warm water, but that might change by Sept. If you came out the east entrance then I would hit the North Fork of the Shoshone river and there is pay camping along the river. At Cody is E. Newton lake just north of town that normally fishes really well, no need for a boat, just wade and concentrate on the brushy edges. Heading south from there I would hit the Wind River below Boysen Reservoir before it goes into the canyon. Two pay campsites along the river before it hits the canyon section. Note, if you want to fish the Wind River canyon you will need an Indian Fishing permit as that land belongs to the reservation.
We also have a member that lives in Red Lodge, hopefully he will see this post and offer suggestions if you decide to go through that area.
No matter the route you take there are lots of opportunities for fly fishing, good luck!
I will be a week ahead of you. Fishing in the Wind River Mountains over the holiday weekend with my sons. Early Wednesday I dump my littler brother at the airport in Jackson and head south camping and fishing through the week. I intend to hit the Yampa, Frying Pan and ??? on my way back to New Mexico. If you want to shoot me a PM I can get my cell number to you and will gladly let you know how it is going when I'm near civilazation. Since I am escaping from reality for the week, I won't have a computer or web access until I get back on the 9th or 10th.
Razz: Good point about the Fying Pan, that might also be a good stop along with the Roaring Fork as you can hit hwy 133 at Carbondale and head SW to hwy 550 and then south to Teluride. Wayne, if you decide to hit those rivers be sure to stop at one of the local fly shops in Glenwood Springs, Carbondale or Basalt and buy a river map, that will detail all the public access points. Also, the Crystal River follows hwy 133 and there are plenty of public access points.
I was just in that area a couple of weeks ago; here is what I found.
The Crystal river is very low and slow along 133 with a lot of sediment in the water. If you get above Marble,CO the fishing is great though.
Frying pan river was in great shape and busy 2 weeks ago. Water is (as usual) cold behind the dam. Mysis, caddis, midges, etc.
The Roaring fork was low and 'wadable' in Glenwood springs. A few hours drifting large nymphs produced a few fish (stonefly larvae, 20"er, copper john, big hoppers). There are some big fish in the roaring fork. The evening and early morning bite were on, but the fish totally shut down when the sun gets up high (deep nymph rigs?)
Have not fished the Colorado recently. It was slightly off color and low, It looked pretty good actually but I did not get a chance to fish it.
Taylor river outside of Gunnison: Have not fished since last year. Lots of large picky trout at the tailwater. The river below is beautiful and less crowded.
High lakes above telluride. Fished there last summer at a lake around 12,000' (above the falls). Only fished 1/2 hour and caught a 18" cutt. Small creek and fishing ponds through town.
The main rivers are all pretty low this year. Fish are hanging deep and hiding out through the day. A lot of people have been fishing higher altitude rivers and lakes this year (including myself). It has been the salvation of the season for sure.
Lots of fishing along the Gallatin.. all the way down Highway 191 into the park.
If you're buying Montana and YNP licenses.. no worries.. but have them before you go south, so you don't have to worry mile marker 30 (4 corners in Bozeman is mile maker ~82) (once inside the park boundary, it's 55 and they use radar - be careful - lol)
Good shops at Bozeman in 4 Corners, another in Big Sky .. you'll go right by.
Smokey right now.. a few fires started yesterday.
Allow time in West Yellowstone to check out the fly shops - I think there's 5.. Blue Ribbon , Arricks are musts.