Ashford has some of the strongest Airbnb occupancy rates in the state, and lower average purchase prices than many other mountain markets, although prices are going up as this quiet town gains more local and national awareness.
Packwood is a popular cabin / vacation town, close to one of the entrances to Mt Ranier & White Pass Ski Resort. There's great Airbnb traffic there, with average ROI as high or higher than almost anywhere else in WA. Because Packwood has Gigabit internet (Seriously, as fast or faster than the internet in Seattle!) it's also becoming a popular destination for remote & nomadic workers. Packwood, like many cabin markets, is appreciating rapidly, and I think it's a good place for Airbnb investors. There's currently no significant or restrictive Airbnb regulations, and as the town is in unincorporated Lewis County any future regulations would have to come at the county level – something that county commissioners have not expressed an interest in doing so far. I sold a Cabin in Packwood to an Airbnb investor client a couple months ago, and their project is turning out great.
Another area i've been excited about are the the towns along highway 2 heading towards Stevens Pass (Gold bar, Index, Baring, Grotto and Skykomish). I personally own a STR in Gold bar and know a few other investors who own STRs that are performing great.
The biggest challenge i've experienced with owning a STR in more of a remote location is sourcing contractors, cleaners, property management etc.. You can still find people but it can be a bit difficult compared to sourcing people in the greater Seattle area. Hope this helps!