Well, my stay at the Tinhouse was a total joy. The place itself is fabulous, full of all kinds of neat old stuff, not to mention a grand view of Elliot Bay. It really can't be beat. There's a ten minute walk to the Light Rail station, which will take you downtown. So, you can definitely get by without renting a car (unless you want to travel to some of the awesome parks or islands ... and even then, you could find a tour for that instead; I did rent a car to go to Mount Rainier, but it would've been cheaper to do a tour).
Leslie and William are super-duper cool. We had a couple of really nice conversations. I'd recommend them and the Tinhouse in a heartbeat!