Well, within Portland itself, you have a few nice hang-out and waste time opportunities. There's Powell's Books (it takes up a city block, and a couple stories). They're easy enough to find online, where you can get directions to the store itself. Their Archery section is lacking a bit, but the larger "Outdoors" section is quite large. To give an idea about size, I like to look at the Philosophy section, if it's one or two shelves.. it's normal, Powell's has two aisles. Lots of subjects to look at, a book worm could spend days in here.
In town there's also the Rose Gardens, which is worth seeing in the summer. Washington Park Zoo is just outside of town, and they always have some fun stuff for the family. More interesting to me personally is that OMSI (Oregon Museum of Science and Industry
www.omsi.edu ) has the Body World's Exhibit until September (I think). This is the thing where they have real human bodies stripped to the muscle, then posed in "active positions". It's sort of sick in a way.. but also incredibly compelling.
If you wish to travel outside of town, I'd throw my vote in for the Tillamook Cheese Factory, buy some curds while you're there, won't regret it. In that same area is also an air museum or two, worth going to see if you're into old planes.
To the East you also have Hood River and tons of hiking in the gorge. Ted Fry's Shop (Raptor Archery) is in Hood River, and I'm sure he can point to local outdoor's things to do. On the Washington Side out there, you are getting close to Indian Heaven and the Berry Fields in Gifford Pinchot National Park. Here, during late August/September you can find fresh Huckleberries (limits apply, may want to talk to the rangers out there).
As mentioned already, Mt. St. Helens is nearby, as is Mt. Hood, and even Mt. Adams. All are worth seeing if you've got the time. In particular, if you're into volcanoes and the things around them, up near Mt. St. Helens are the Ape Caves (A google search will pop those right up). It's a neat, and relatively easy trek through an old lava tube, you get to go in one side and pop out the other. I believe that in the summers they even have tours.
So that's what I can think of off the top of my head. Good luck and have fun, if you need any additional ideas or more specific instructions, feel free to PM.
Ivan
edit: I didn't even get into food.. my goodness, there's too much to list, so I'll quickly spell out my top three casual/family friendly restaurants. Over in Vancouver is Juliano's Pizza (Take 205 north, it's faster). In Camas there's Twilight Pizza Bistro (Are you getting that I dig pizza?) And any number of McMenamin's, these are bars.. but also have kid-friendly pub areas. The Kennedy School was already mentioned.. this is a great example of the chain.
For not-so-kid-friendly.. I'll just mention my favorite Pub, The Horsebrass in Portland (they've got a website
www.horsebrass.com). The Bridie with a Banger on the side, and a pint of Guinness is just about heaven for me. They used to allow under-age folks before a certain hour, could call and check.