The Skykomish is a standard, runs most the time class III-IV locally. If you're lucky, the Middle Snoqualmie or Upper Green Gorge will be running. They're class III-IV and really nice. The Lower Green is more III-II but is a beautiful gorge with a wilderness feel(no houses). The Sauk is also a nice III-IV run with a wilderness feel.
I ran the Dungeness out on the Peninsula on Monday for my first time. Nice III+ run with no houses, though lots of wood. Whatever the level was Monday, it was a little low.
I can't comment on more difficult runs.
When studying runs, it's best to cross reference between the AW site and the PP river pages and understand that folks sandbag a bit. That is, if you ask for a class III run on PP, they may well offer you a stiff class IV run. Do your homework. http://
www.nwrfc.noaa.gov/rfc/ attempts to predict river levels with varying degrees of success.