Portland has so many spots and parks. When I visited my sister there a couple months ago I skated 11 different parks in three days. There's probably about two dozen good parks in the greater Portland area. Definitely a great city if you love transitions.
-Every time I take a trip up I make it a point to visit Burnside. It's a good place to measure your skills and how much you've progressed. Can't match that vibe. Super burly and gnarly locals. Great to skate when it's raining.
-There's also a small indoor park called Commonwealth with a slippery concrete bowl.
-One of the best parks I've ever skated is Ed Benedict skate plaza. Good flow and size for a street park. I think some of the ledges were made of marble or granite too! Absolutely a must hit destination with a wealth of fun obstacles.
-Pier park is a nice park with a full pipe.
-Glenhaven has some sweet brick banks, but it's next to a high school. So make sure to get a session in before class is out and rush hour.
-You could spend days just rolling around downtown Portland and spot hunting. I found a bunch of fun stuff near the Jeld-Wen Field soccer stadium.
There's all these free water fountains called bubblers everywhere in the city which are great when you're thirsty and wanna prolong your session.
-There's a few good parks in the suburbs of Beaverton too. The Beaverton skatepark is cool because it's pretty large and has a conrete section and a wood ramp/banks section.
Check out
http://skateportland.org/Yelp, sk8 park atlas, the concrete disciples are valuable resources too.
I just make sure to do a bunch of research online to plan routes and minimize driving time.