Oregon Trip - Mt St Helens or Waterfalls??
 

My family of 4 (husband, two teenage boys and myself) are staying in Portland this summer as the last leg of a Pacific NW trip.

While in Portland, we plan to explore the city but we will have a free day and can't decide if we should visit Mt St Helens or go East to visit the beautiful waterfalls such as Mulnomah Falls, Latourelle Falls, etc. It seems like each trip would be a day trip so we can only do one. We are all history and science buffs but we also love seeing new landscapes.

Any thoughts on if Mt St Helens or the waterfalls would be the better choice?

Where is the first leg of your trip? My advice is to stay in Hood River and see the waterfalls on the way to the airport.
The last time I tried to get to the visitor center at Mt. St. Helens, the road was closed by snow about 5 miles from the visitor center.
See the waterfalls and then drive Rt. 35 south from Hood River up to US 26. See Timberline (maybe stay there).
Visit Portland as a day trip instead of staying downtown.

We are staying in Seattle for 3 nights then driving to Olympic National Park where we will stay for 3 nights. Then, we'll drive down to Cannon Beach and then over to Portland. We are staying in Portland 3 nights and exploring the city for one of the days.

We'll fly out of Portland so the last day is open.

This trip will be in July so I'm not sure if the waterfalls are low that time of year or not.

Definitely the waterfalls.

The waterfalls are year round and less prone to seasonal drying-out than, say, Yosemite. And this has been such a snowy winter that even those that are fed by melt water are still going to be booming in July.

But I don't know that it has to be an either-or question. After Cannon Beach you could head back over the river to Cape Disappointment (take a few minutes at Waikiki Beach for great views) then head east on WA 4 toward Longview, which will put you on I-5 not far from the turnoff to Johnston Ridge on Mt. St. Helens. It would be a longish but not impossible day to end up in Portland following a route like this - https://goo.gl/maps/vpsJk9M2s8H2 . Alternatively you could visit Cape Disappointment on your way south from Olympic NP, in which case the drive to Johnston Ridge would be a bit shorter. The north shore of the Columbia is quite historic and fairly scenic in places, unlike the roads on the Oregon side.

But if it IS a choice, then the Gorge in a heartbeat. In fact, if you're "history and science buffs," then I'd consider adding a day to the Gorge and Mount Hood area, even if it means taking a day from Portland.

If you head an hour east from Hood River, you can visit the Maryhill Museum and Stonehenge replica, and the change in landscape, climate and geology will be sensational. Or an hour south from Hood River and you're at Timberline Lodge on the side of Mount Hood. You can ride a chair lift up to one of the permanent icefields/glaciers on the mountain, and drink in the marvelous scenery as well as fascinating history (WPA, CCC and all that.)

Plus you should visit the Bonneville hatchery near Bonneville Dam, and your boys will undoubtedly like seeing all the windsurfers and kite surfers on the river at Hood River, the self-proclaimed world capital of the above.

Wow - thank you so much for the information. I will re-evaluate things to try to work some of your suggestions into the schedule. This is our first time to the area and we are super-excited. I hope I will even want to come back to Texas :)

If you are flying in to SEA and out of PDX, I hope you are not paying a drop off fee on the rental car.
There are at least 2 ways to avoid this if that is the case.
If you rent from SEA, just drive back to SEA and fly home from there (3.5 hours on I-5).
The other more complicated way is to have the driver take the car back to SEA and turn it in and take the train back to Portland (downtown) to get back together with the family.
As of today there is over 170" of snow at Timberline.
The east end of the TriMet red line (light rail) is at the PDX airport.

My husband and I hiked the 4 mile trail up and around the waterfalls last year in July. The hike was beautiful and not too strenuous. Due to the increased rain this season as well as being in a rain forest - do not get near the edge of the trail. At the 3 mile mark, I stepped aside to speak to my friend and I ended up rolling down a heavily forested steep hill before hitting a tree -perhaps 50 feet . About 18 inches of the side of the trail had given way. All was well, but be vigilant and stay away from the edge!

The waterfalls around Portland are absolutely beautiful, and worth seeing. I've been to Multnomah Falls a couple of times and love the scenery of the hike.

Yes - the waterfalls! They are gorgeous and the Columbia River Gorge is, IMO, one of the most scenic areas in the US. There are many great hikes in this area.

Thank you everyone for the ideas and comments. This has been really helpful!