While in the Columbia River Gorge, you might stop at the Bridge of the Gods at Cascade Locks, Oregon. RV parks, a great buffet style restaurant with lots of antiques (Char Burger) with large windows overlooking the river with a view of the bridge. One of my favorite spots in all weather. Parking sometimes difficult at Char Burger so I always plan to pass by on non-holidays.
And of course you'd want to spend a few hours at
Multnomah Falls. Hiking to the top of the falls is an adventure and not all that strenuous.