Portland in August
The Pearl Bakery ( eat there or take it with you)
Mothers ( great breakfast! ) also great comfort food dinners
The Heathman ( very nice )
Fullers ( funky )
Red Star Tavern ( in the 5th Avenue Suites Hotel) great breakfast & brunch
Near where you are staying...( Portland Streetcar will get you all over town )
On NW 21st, Serratto ( Good Italian)
Cafe Mingo ( really good Italian, always lines )
In the Pearl
Henrys Tavern - (good food, big space, large servings ..comfort food)
Everett Street Bistro ( just plain good food -breakfast/lunch/dinner)
Southpark ( seafood-excellent)
Carafe ( French bistro)
IMO the best brunch in town is at Simpatica, Sundays only, starting at 9, SE 9th and Pine (across the river).
Mother's is usually a good breakfast too, and if you go, the extra $$ for the french press coffee is worth it. Their lunch and dinner menu is heavy on comfort food. They take reservations...which are a good idea if you want to go there.
On NW 21st my favorite is Basta's. Great happy hour deal starting at 5, best $20 steak in town, yummy carpaccio, fabulous mussels in a saffron/wine/cream sauce, fabulous crispy 1/2 chicken, very good caesar salad, always good service/prices/value.
If you love seafood and like it raw (as in sushi) Murata (downtown at 200 Market) has some of the best in town. Carafe, the French bistro recommended above (which is also very good) is in the same building.
Across the river on SE Hawthorne near 20th is Ken's Place. Lots of comfort food to be found there.
If you are looking for a funky upscale dance clubby bar experience, aura, across from Powell's might be fun. Great ladies room!
If you want to taste local beers and are looking for a pubby bar atmosphere try Rogue in the Pearl, or go to the New Old Lompoc which is near where you are staying (great home brewed root beer too!).
The recommendations of Seratto and Mingo are good but they may not fit your definition of 'not expensive'
Justapasta might be a better fit.
Also on 21st is Ken's Artisan Bakery.
I think Ken's croissants/pastries are better than PearlBakery (where I prefer their breads).
Also for french pastries near NW21st :
Haven't been there myself but a French person highly recommended it to me once.
If you're willing to travel, I would recommend Pambiche on the east-side for Cuban - which to me is inherently comfort-food-ish.
If you are willing to venture into Sellwood, go to Gino's (8051 SE 13th Ave., Portland, OR 97202, 503-233-4613). It has been our favorite place to steer or take out-of-towners for many years now. Excellent, huge wine list, including a separate list of options for under $20 a bottle. Generous portions, traditional Italian country style comfort food. Entrees run about $15 -- if you go for the salmon or a steak, the price will go up. We generally stick with the ravioli, one of the daily specials, or the seafood pastas, which hover around the $15 mark.
The daily green salad is always something different & special -not your standard tossed greens with standard dressing. The house dressings change daily and are always tasty. The
small dinner salad with entree is excellent, too. Their caesar is wonderful, but a matter of taste. It is not a purist's caesar. Some think it's too garlicky. We love it. Beware: The "small caesar" (around $10.00) feeds 4, and there is not a smaller version available to order.
The vongole is fresh & light & wonderful - manila clams in the shell in a garlicky clam broth served over spaghetti. The mussel pasta has a little puttanesca in the broth and is great. If you can't decide, they have a mixed shells pasta that has 1/2 clams 1/2 mussels. The ravioli of the day is always good. During crab season they have a superb spicy crab pasta. The seasonal and vegetarian specials on any given day are creative. We had a pasta a few weeks ago that had fresh favas, morel mushrooms, fresh ricotta & garlic. We're still swooning. Their spring pasta (just missed it) features fresh spring peas, garlic, & brie. Unbelievable.
TIP: They don't take reservations, so get there early to avoid a wait. They open at 4:00. We usually try to get there sometime between 4:30 & 6:00.