I will be driving to the Salish Lodge for breakfast and then walking down to see Snoqualmie falls. What else is there to do near this area in the afternoon?

Nothing like a piece of cherry pie and a hot cuppa java.

Visit the gift shop and spend money on ridiculous stuff, walk over the bridge and hike up the trail, or, there's a bowling alley in downtown Snoqualmie (near the outdoor train museum, and giant tree stump memorial).

Hi,
Yes, you can go to the Mar-T cafe in North Bend (a short drive) and have pie and coffee and reminisce about the Twin Peaks glory days for the Upper Snoqualmie Valley. There's also an outlet mall next to I-90 there.
Or, you can drive north on SR 202 & 203 down the Snoqualmie Valley, and visit the Carnation research farm (near...Carnation!), where it all began, now run by Nestle, and see the flowers and contented cows. It's a lovely country drive.
Or, continue east on I-90 from North Bend and an hour later or so you're in central - eastern Washington, ranches, red rocks, canyons, desert, old west.

NOTHING!

I thought the Mar-T had closed?

Drive east on 90 20 minutes and see the ski area with tons of snow mounded up everywhere. There is a fun tubing rental center there. Or go west on 90 to the town of Issaquah and walk around the Salmon Hatchery. If it is not raining there is a lot of hiking on the mountains all around. Nicely marked at the bases. Yes see that big tree stump too that the above poster mentioned. The outlet mall has Gap, Nike, etc if you are into that sort of thing.