Multnomah Falls
Google Maps will tell you take Exit 31 on I-84 to visit Multnomah Falls.
That is not how the locals take their friends to visit the falls, so I’m going to tell you the better way, that isn’t much longer.
Get on I-84 going east, but take Exit 22 for Corbett. You will go up the hill and turn left on the Historic Columbia River Highway. This will take you up to Crown Point, where you can stop at the Vista House, with a spectacular view of The Gorge.
Continue along the highway to visit many waterfalls (including the famous Multnomah). My personal favorite is Horsetail Falls, as you can hike up the hill to see Upper Horsetail Falls where you can walk behind the waterfall.
The hikes here can easily take the entire day (you can have lunch in Multnomah Falls Lodge), but I would recommend ending your day at The Edgefield, an artsy lodge with pretty good restaurants and bars.