The upper forks of the Snoqualmie river are intimate, fun little trout streams. Most folks fish the middle or south forks. Not a ton of bug life, but tons of eager fish that love dry flies.
Below the forks, but above the famous Snoqualmie Falls, there is a ton of easy water, eager trout and plenty of access.
Below the falls, its predominately a steelhead and salmon river, but it does receive a HUGE run of Sea-Run Cutthroat trout in September.
The pristine surroundings and easy access from Seattle makes this a great place to spend a day fishing.