Check out: Frisbee Golf - frolfing at Pier Park, Dabney, Rooster Rock, Blue Lake. These are also great places to walk and relax. Hiking the Columbia River Gorge: Close to Portland, and full of waterfalls. Look into Wahkeena, Wahclella, Multnomah Falls, Horsetail, Latourell. Great viewpoint: Sherrard Point on Larch Mountain. Other Hikes or walk in the city: Forest Park, Marine Drive Trail, Mt. Tabor park, Powell Butte, Cathedral Park & the St. Johns Bridge are super. Other notable parks: International Rose Garden, Japan Garden (entry fee), Grotto (fee), Rhododendron Garden (fee), Peninsula Park rose garden. Watching the sunset at Skidmore Bluffs is great.
The Coast (Canon Beach, Astoria, Manzanita are great), Silver Falls State Park, Ape Caves, Saddle Mountain Hike, or visiting Hood River, Bend, Seattle, kayaking at Scappoose Bay, Wineries in the Willamette Valley... Mt. Hood is close, and there are many hikes and lakes and activities up there. Visiting Timberline Lodge is fun.
A few breweries: Base Camp, Great Notion, Ex Novo, Stormbreaker, Breakside, Lucky Labrador, Migration, Cascade Barrel House, Threshold, Second Profession, Deschutes, are good spots. Bars: Horse Brass Pub, Belmont Station, Quarterworld, Donnie Vegas, Alibi, Bar Bar, Bye & Bye, Wilder, Tough Luck, Buehlaland, Rimsky-Korsakoffee House, Pied Cow Coffeehouse, Roadside Attraction, Elvis Room, Hale Pele.
Some of our Favorites: Bollywood Theater, Gado Gado, Omas Hideaway, Peoples Pig, XLB, Pine State, Killer Burger, Franks Noodle House, Tin Shed, Ps & Qs, Pho Oregon, Pambiche, Kens Artisan Pizza, Zachs Shack, Screen Door, Tamale Boy, Hat Yai, Pizza Jerk. Food Carts are awesome. Eat every meal at a food cart. Our Favorite Pods are: Piedmont Station pod, St. Johns Food & Beer Porch, Cartopia, Cartlandia, Eastport pod, Collective Oregon eateries, John's Marketplace, Mississippi Marketplace, Portland Mercado. Donuts are big: Blue Star, Pips, and Angels are pretty good for these. Coffee is big too. You'll find great coffee on every block, so I wouldn't seek out anyplace specific. But if you're close, Just Bob, Proud Mary, and Bipartisan are cafes we like.
If you want to check out Downtown Portland, there is fun stuff: the Saturday Market (on Sunday too); Big Pink building (getting a drink at the restaurant on top for good views); take a walking tour; Pittock Mansion; the Rose Garden; the Japanese Garden; the waterfront & bridges (Tillikum & steel are favorites); Powells book store; Portland Art Museum. While you are down there check out the alphabet district (walk NW 21st & NW 23rd).
Stuff that doesn't fit in a category: McMenamins properties are really fun, they have food and drinks and activities in unique locations. The best ones close to Portland are Edgefield and Kennedy School, but Chapel Pub, White Eagle, St. Johns Theater, Bagdad & Back Stage bar, Al's Den, are also worthy spots. If there is a roller derby bout scheduled that is a fun activity. So is seeing a Portland Pickles baseball game.