Arriving at Seatac (or whatever it's called) at 3:30pm.

I'm flying out of Sea-Tac -- short for Seattle-Tacoma International Airport -- about 2 hours before you arrive. One depressingly interesting bit of trivia is that the town adjacent to the airport incorporated a few years back and the town is called SeaTac. Is that low-budget derivative, or what???

If you happen to be working downtown, a cheap thrill is to take the ferry from Coleman Dock over to Winslow, have some fish and chips, then take the ferry back. It's still light pretty late and you can get some nice views of the city.

Good idea on the Cascades. A short version is to take I-90 east, go south to Yakima, then take Chinook Pass back through Mt Rainier Natl Park. A longer day is east on I-90, northeast to Wenatchee, pause for cheeseburger, north to Winthrop, then west on North Cascades Highway through N. Cascades Natl Park. If you've ever read the first chapters of Kerouac's Desolation Angels, this route may prove irresistable -- the highway wasn't built yet when he wrote about his stint as a fire lookout on Desolation, but you can get an idea of what is was like. It's a longish drive back down I-5 to Seattle ('course you could always hang a right and go see Vancouver!!)

Another not-too-hard trip is to take a ferry from North of Seattle (Edmonds) cross to Kingston, then drive up to Port Townsend and Port Angeles. You can get pretty high up into Olympic National Park to Deer park Ranger Station (gravel road) or Hurricane Ridge Visitor Center (paved) in your rental car. If you started fairly early, you could even drive counter-clockwise around the Olympics -- go see the Pacific beaches.

FYI, my friend tells me that the South/International arrivals area is a mess of construction lately, so be prepared for some extra fun getting through Customs and such.

Have fun!