As said, you'll have to pick one or the other (cost or land). Traffic in Seattle proper can be a bear, so figure that in too.
If you do find yourself doing tourist duty at Pikes Market, this is our fav restaurant:
Place Pigalle Restaurant and Bar - Seattle, WA
From Victoria the ferry rides are fun. The San Juan's are spectacular I have a customer with a house on Orcas - really magical place. If you do ride the ferry then drive, take it to Port Townsend, then drive a bit of the peninsula. If you do ride ferries be sure to book in advance or you could find yourself waiting for a couple of departure cycles. In summer it's pretty heavily traveled and all it takes is a semi truck and a half dozen cars are left behind. Head inland from there towards Ranier or Mt. St. Helens. Hwy's 12 & 410 wind through the southern portions of those areas and would leave you off south of Seattle and the airport on your way out. Coulee Dam is fun, and could be a good eastern boundary.
Beautiful country up there. Not too shabby down here in Northern OR too.