华州西部游行程

If you are talking about metro Seattle, yes 3 days might be adequate. But if you want to cover anything above and beyond, plan at least 7 days or more
Here is a few must:
-Metropolitan Seattle: 2 days
-Mt Rainier NP: day trip 6 hours driving round trip
-Olympic NP: at least 2 days are recommended. Many people go there for the day but miss the rain forest and the most scenic area - the Pacific Ocean side of Olympic NP. This is one of the 3 temporate rain forests in the world.
-Mt Shuksan/Mt Baker: Day trip - 6 hours of driving round trip; hidden secret and most photographed peak in N America
-San Juan Islands: day trip perhaps longer. Most people get to Friday Harbor but I personally think Orcas Island is more laid back and scenic with a view of all the surrounding islands and snow capped mountains in WA state and Canada rising above ocean - nothing like it anywhere.
-Mt St Helen: 6 hours round trip driving - the only N America active volcano errupting as we speak - if you've made it this far, you might as well go to Oregon too.
-Hwy 20; Day trip; Deception Pass, Mt Erie, and Anacortes on the west end and Northern Cascade National Park going East. Glacier peaks and the Pacific Ocean in a stretch of 2 hour drive
-Hwy 2
-Mountain Loop Hwy: Big Four Ice Caves is the highlight. This area is nicknamed the Alps of North America for a very good reason. The ice caves won't be visible usually till June when snow melts.