Go to the Big 4 Ice Caves. It's up in your neck of the woods, and it's very easy. About a mile or so long (each way), gentle slope. Hikes to a scenic valley with glacier-like deposit of snow, the snow has streams running underneath causing ice caves. Pretty cool, very easy hike.
If you want a wonderful hike, do the Ape Caves hike down by Mt St. Helens. This is an ABSOLUTE must do hike with the kids. Just make sure to bring headlamps, flashlights & gloves. The hike is underground, a couple of miles long. The cave was formed by a lava tube eons ago and you hike up thru the cave, and can exit at the end and come back above ground, or return hike backwards thru the cave. You do have to scramble over some boulder piles, and scamper up some inclines. Great hike for kids. Very worthwhile.
Google the names for more info.