Let us know how the ride went!
I see from your other posts you're just starting out on riding. Hopefully you've found a site called bikely.com that lists lots of rides that people have put together in this area. It also allows you to map out rides you are thinking about taking so you can figure out the mileage in advance.
Another good source for ride ideas is the "route maps library" at the website of the Seattle Bicycle Touring Club.
And, also, check out the event schedule for the Cascade Bicycle Club. The Chilly Hilly is coming up on Feb. 24. It's a hilly ride on Bainbridge Island, about 33 miles. A couple of the hills are indeed challenging but you can skip them if you are a good map reader and make the ride much more doable. If you don't feel quite ready for the Chilly Hilly in February (or if the weather is lousy), it's still a terrific ride to do in the summer.