I know Portland best, so I will suggest a daytrip there. Voodoo doughnuts. Perhaps Pied Cow for a quick lunch thing. And the main reason for the Portland trip? The Portland underground tour. It happens less frequently than the Seattle underground tour, so you'll have to look in advance, it's not a regular event at all, but very well worth it.
The reasons for Portland having an underground are radically different from Seattle's. It is full of (true) stories about opium dens, white slave trade (there was a route from SF, to PDX to Seattle, etc) and Portland was the origin of the word "Shanghai'd" where bar patrons would fall through a trap door, be clubbed or drugged and wake up as a crew member on a ship headed for Shanghai. You said these girls studious - well, this is a very different kind of history than they'll read in a book. In fact, the historians think there are other deeper levels, but they have not found an entrance to them.
ooh, looks like tours have gotten more regular! I know a Portland trip is a big deal, but you won't regret a pdx underground tour. It's really different than the Seattle underground tour.
Seattle-wise, I would suggest breakfast at golden gardens and a trip to the farmer's market.