There's still a fair amount of water coming over Snoqualmie Falls, and you can hike down to the lower falls area. You might consider doing a two-part day, one half in the city, the other half out to Snoqualmie Falls and the "Twin Peaks" country. Maybe stop for a (decent) burger and sensory overload at the Triple XXX drive-in in Issaquah, right off I-90.
Here's a map showing the Snoqualmie Falls portion -
https://goo.gl/maps/cXesjgubKGiB5H8D7
Snoqualmie Falls ? Official Web Site
Triple XXX Rootbeer Drive-in