Trip Planning

I have an upcoming business trip to visit a client in Seattle, WA. I'll be with the client for about 3 days and they will be showing me around that area a bit in between our business meetings. BUT I have decided to add a day of personal travel to that area ahead of time. I have NEVER been to that area of the country so I need some suggestions of what to do with my 24 hours of ALONE time in the Oregon/Wa area. One thought has been to fly into an Oregon airport, rent a car and drive the coast line into Wa and then go over to Seattle. I would expect to have from a Wed afternoon to a Thursday afternoon on my own. All of you know my love of taking scenery and flower pictures. So what should I do with my 24 hours?