Taking the Old Columbia Highway from Portland, the first waterfall is Latourall Falls. It's a fairly easy quarter mile hike down to the pool.
The hike to the top of the falls is a bit harder. Yeah, look how far up you have to go! :)
I didn't go to the end of the trail (it may go all the way to Larch Mountain!) but did follow the trail along the creek for a ways.
The second stop along the Highway didn't have a parking lot, just a turnout east of the bridge. Shepherds Dell is a 400 yard trail down from the highway
From the end of the trail you can see the upper falls
and the bridge you drove across.
The third stop is Bridal Veil State Park which has 2 trails. The first is a half mile scenic trail loop above the Columbia River.
The Falls trail is an easy two thirds of a mile (roundtrip) down to the pool.
The fourth stop is Angels Rest, a 2.3 mile hike to a viewpoint. You can also hike to the 5th stop, Wahkeena Falls, which is a 6.4 mile trail. There is also another viewpoint farther along the trail called Devils Rest (8 miles, I think, and it continues on to Larch Mountain). It was late enough in the day that I didn't hike up there (I actually don't remember seeing that stop before so I will be going back!) but continued on the Wahkeena Falls.
You can see the Wahkeena Falls from the parking lot
but it's only a .2 mile hike to the bridge.
The trail continues upward - steeply -with many switchbacks and I never did get to see the upper falls. This is an eastward view of the Columbia River from Lemmon's Viewpoint.
I decided to keep folowing the trail as long as it followed the creek...
and came across Fairy Falls.
Multnomah Falls is another half mile by trail or quarter mile by car.
You can see all the pictures here