You can absolutely visit both the waterfalls and then make the “loop” around the mountain to visit Mt. Hood thanks to extended summer daylight hours, or if you plan on getting an early start.
I would suggest taking I-84 east, then taking the Corbett exit to join the historic highway. While most people start in Troutdale, you really won’t be missing any of the major sights, and this will save you some time if you plan on making the loop around the mountain.
After you reach Corbett, make sure to stop at both Women’s Forum and Vista House/Crown Point. Both spots have incredible panoramic views of the Gorge. Vista House is a beautiful historic building, originally built as a “rest area”, but you will have a hard time believing that after you see it.
From there, you will enter the “waterfall area”. Besides Oneonta Gorge and Multnomah Falls, you will definitely want to stop at Latourell Falls, Wahkeena Falls, and Horsetail Falls. Let me know if you would like me to suggest any hikes in this area. There are some nice, short ones in this area well worth your time.
Shortly after Horsetail Falls, you will rejoin I-84. Continue on to Bonneville Dam. The Fish Hatchery here is well worth a stop to see the HUGE sturgeon, and if you have some extra quarters feed the trout.
From there, return on the freeway east and you can stop either in Cascade Locks for lunch, or continue on to Hood River to eat. It all depends on how hungry you are. There are some great brewpubs in Hood River.
From Hood River, you will travel on Highway 35 around Mt. Hood. This will take you through the heart of the “fruit loop“, filled with orchards, wineries, and other attractions.
You will see some beautiful scenery as you travel around the mountain and then join Highway 26. There are some great places to stop for views of the mountain. Let me know if you would like some specific suggestions on scenic spots.
One definite MUST STOP is Timberline Lodge. The craftsmanship of the place is incredible. It was all hand built during the depression. From there you will travel highway 26 and head back towards Portland.
Let me know if you want any dining suggestions, or have any more questions. I realize this is probably a little information overload, but wanted to make sure I got everything covered for you.
Have fun planning your adventure!