Olympia!! Not even close. Olympia national park is one of the coolest parks that I have been to in the US. Yes, you will have to take a ferry from Seattle to Bainbridge Island but it s not that much. It is like $12 for you and your car each way. You should go south, however, after leaving Olympia and go to Lake Quinault and stay at the Forest Service Lodge. Get reservations ahead of time - it is very, very cool. Another great place is Kalaloch Lodge on the coast. Also Forest Service and very, very nice. Here are sites:http://www.visitkalaloch.com/index.cfmhttp://www.visitlakequinault.com/Have fun!!
tough choice but I would pick olympic nat l park--it has the mountains, rain forest and coast...mt rainier just has the mountains (which are amazing in their own right)...a ferry is not that expensive so dont let that persuade your decision