Not sure about Olympics being any better weather then Cascades; would assume its quite the opposite. Also, be prepared to carry bear canisters as they are required thru lots of parts of Olympic NP.
We have just recently discovered a village of Holden in Glacier Peak Wilderness. It can only be reached by boat, and it is situated among the most beautiful places in the world i've ever seen. it gives you instant access into the heart of the wilderness, without roads, noise, tourists, and development. it will give you this feeling "im in the middle of nowhere" - the scenery is just gorgeous and the village is so unique! its only a 3 hr drive from Seattle to chelan landing. you'd also experience on of the deepest and pristine lakes in North America. there are turquoise-colored glacier lakes of an unforgettable color just 4 miles up the trail, with cascading waterfalls, huckleberries, Yosemite-like cliffs...
Day 1: take lady of the lake express, arrive Lucerne.
Take bus to Holden
Hike to Hart lake, make camp there.
Day 2: explore to lower Lyman lake, Cloudy pass, Upper Lyman Lakes. Return to camp (about 12 miles).
Day 3: Hike to Holden, make sure to have a communal lunch over there. Take a bus to Lucerne, get on the lady of the lake, drive home (stop at Leavenworth for dinner).
just a suggestion... pm me if any questions. have fun on your trip! hope the weather holds.