Planning a bike trip. Where should I go?

A little over a year ago I did a week trip to Crested Butte and rode a bunch of classics and had a blast. Did 401, 409.5, Teocalli Ridge, Reno-Flag-Bear-Deadmans, Dr. Park and a couple other things around town. I'm going to try and make another trip this year. Possibly second week of August or late September as those are the best times for my work schedule. I'm looking for a place with a similar out in the mountains feel. The elevation in Crested Butte was pretty rough though and seriously impacted my performance on these longer rides.

I'm hoping to go somewhere with mountains where I can do some long pedal all day till my legs fall off kind of rides. Not interested in park riding at all. Hoping to find some solitude not crowds. Also a factor is if I end up going in August would be heat in some places. I hit SLC last year while I was there for work and the week before it was over 100° every single day. North Carolina (Pisgah etc) sounds great but seems like it could be ridiculously hot and humid in August. So far top of my list are Tahoe/Truckee/Downieville, Bellingham WA or Squamish. A little concerned Bellingham and Squamish might be super wet. Also hoping for like 2-3hours max from a major airport. Crested Butte was about 4 from Denver that was doable but a bit long.