Depending on how long your stay is... some places I would suggest to eat while here:
The Roxy: Similar venue to Voodoo Donuts, only with diner food.
Rimsky-Korsakoffee House: Very "Portland" coffee place. Great for desert. Come here later at night (after 9), but remember it's cash only. Also, make sure to use the bathroom upstairs.
Papa Haydn's: Fantastic desert at about $8 per dish. Come in for something sweet, but be prepared to wait 30 minutes for a table if you don't have a reservation.
Saburo's Sushi House: Best sushi in Portland. Big pieces, and great prices. This place does NO reservations and is ALWAYS busy (dinner only) so you're looking at a minimum 30 minutes wait, even in the middle of the week.
The Orignal Hotcake House: Open 24/7, serving huge portions of fantastic breakfast food. Stop by, and make sure to try the hashbrowns.
As for some things to do... that also sort of depends on how long you'll be here.
-If you're driving, try
this scenic drive through the Gorge and around Mt. Hood. It's a day trip.
-Visit the
International Rose Test Garden and Portland Japanese Gardens located in nearly the same place. The Rose Garden will be absolutely beautiful around mid May.
-Hawthorne is a must if you want to poke around town for a more "Portland" experience. Alberta is as well, but you won't be in town for "last Thursday", which is at Alberta on the last Thursday of every month. It's basically a monthly, 20 block long block party.
-OMSI (Oregon Museum of Science and Industry) is actually a pretty neat place, although I'm not sure it fits what your coming to Portland for. It would be on my list, but I'm a major science/engineering geek.
-Pop into Backspace at NW 5th & Couch St. (pronounced Cooch if you talk to a local) for some computer gaming and/or browsing, or sometimes poet reading contests, or local bands, etc.
-Make sure you visit Powell's City of Books at N 10th & Burnside. It's the largest used book store in the world. Go all the way up to the top room and take a look at the Pearl Room, where if you have a deep pocket you can find such things as a signed copy of Huckleberry Finn.
Other than that... what are your interests? What are you coming to Portland
to see?