Go visit Mt. Hood!!! Hiking galore!
Definitely enjoy walking the various neighborhoods in SE, NE, North Portland, E Burnside, downtown, etc. So much good food to be had, so little room in human stomachs.
Also, I know I'm in the minority in this opinion, but it's hot in July. It's not Florida-July-weather where it's muggy and rainy, but it will be dry and there probably won't be
any cloud coverage most days. Last summer was fine temp-wise, but the summer before was excruciating. Be prepared! (It's normally fine at night, for what it's worth.)
+1 to McMenamins hotels
I like the Columbia Gorge as well. This is one nice and nearby day hike you could do:
http://www.oregonhikers.org/field_guide/Triple_Falls_Hike
I know this probably isn't high on your radar, but tax-free shopping
If you have a rental car, you could do a fun day trip with Astoria -> Tillamook / Oregon Coast -> back to Portland (long day trip, though), or split that into two days for more beach time. Such beautiful forests to drive through for this...
Pittock Mansion is nice to visit just to see the view of Portland. You don't need to do the inside visit, just to peer out from the cliff. On that note, riding the skytram at OHSU might be fun, but it's like a 15-minute experience. It's just another way to see the whole city.
Don't waste time at VooDoo Donuts if there's a long line (or, at all really...)
Also, there's all kinds of canoeing/kayaking/whatever down the Willamette River; it's not always all that busy boat-wise, but it can get busy in summer with other kayakers etc. You could also kayak up to Willamette Falls (but not actually UP them; you can get very close), which isn't far outside of the city.
https://en.wikipedia.org/wiki/Willamette_Falls
You might visit Saturday Market downtown (open Saturdays and Sundays) along with any plans for walking around downtown. Also, biking or walking the east side esplanade is nice in a walking-in-a-city-by-the-river way. Little statues and such along the esplanade that relate to Portland history, info plaques on aquatic life etc.
I'll post back if I think of anything else! There are some good Portland/Oregon guidebooks out there that should help you narrow it down, esp hiking guidebooks. Almost too many in fact
Have a fabulous trip!
