Into Seattle every month or so....transporting friend to SEATAC..Usually I just drop off and go back home (Eastern WA) Oct. 31 same trip but friend returning Nov. 5
So would like to do "something" in surrounding area ..
Bar Harbor, Bremerton, ...Even Squim which I realize is about 2 plus hrs..
Even considered {Port Angeles ) and walk on Ferry to Victoria for 2 days?
Anything "east" of Seattle ---already worn out showing relatives around.....
Guess you can tell I am "floundering"
Just reaching out to fellow travelers...
Note: I love prowling thru used book stores..must admit have not exhausted these in Seattle area...
IF you are ever in Ellensburg , drive 10 miles east on I 90 to Kittitas
Bailey's Bibliomania bookstore .Worth the extra miles. .Great bargains..
.buy 2 , one free....awesome assortment ..

Sequim is not a place most visitors have on their radar. My inlaws live there and I would skip it. Port Angeles has Hurricane Ridge, which is a must if weather is good. The Coho ferry is a great way to go to Victoria. I always take my vehicle though as I hate to be limited to just the downtown area there. Port Townsend is a nice little place with a handful of old book stores, and Fort Worden which is quite interesting. Snohomish is a great little town, with loads of antique stores and great little shops and some very good restaurants, all within a few block radius along the river. Bellingham is nice and you could do Chuckanut Drive there as well as Whatcom Falls. Along Chuckanut is the Taylor Shellfish Farm where you can buy fresh seafood. La Conner is a nice little town. Whidbey Island is great.

Various ideas. I'm not clear if you're looking for day trip or overnight destinations, so I'll just mention day-trippable. Google as necessary.

Snoqualmie Falls, Twin Peaks touring - Twede's Cafe, Salish Lodge, Mt. Si...
LeMay car museum, Museum of Glass, Chihuly Bridge of Glass and WA State History Museum in downtown Tacoma
Vashon Island, esp. Point Robinson lighthouse and coffee in Burton.
Bloedel Reserve on Bainbridge Island
Poulsbo and Port Gamble on the Kitsap Peninsula; Chief Seattle's grave in Suquamish
La Conner and Deception Pass
Langley and Coupeville on Whidbey Island
Mukilteo lighthouse and adjacent park
Boeing factory tour
Museum of Flight in Seattle
Museum of History and Industry (MOHAI) on Lake Union.
Antiquing (old books too) in downtown Snohomish
... I'll think of more.

If you're contemplating an overnight someplace (like Victoria) then think about taking the train (or driving, but more like 3 -4 hours) to Vancouver or Portland. Obviously Powell's Books in Portland is a mecca for old book stores, but there are good books (at good prices thanks to the exchange rate) in Vancouver. I'd hesitate about taking the ferry over to Victoria - few sailings and possibly rough water crossing the strait. The train rides to Vancouver or Portland are cheap, easy, and surprisingly scenic.

How about Whidbey Island? I like the Captain Whidbey Inn.

Underneath the north end of the Aurora bridge in Fremont, is a large troll. Part of it was a VW bug. Troll St. goes up from 34th not far from the geocaching world HQ.
You could take an Amtrak train or bus to Vancouver BC and return on the 4th.

So just to clarify the prior posts-- there is both the Chihily glass in Tacoma and a Chihuly museum in Seattle.

I have not made it there yet but the Ballard locks sound interesting.

Not sure if you will be continuing to visit Seattle in December but we went to a gingerbread competition in one of their big hotels. It was really an incredible show.

If you want to visit Victoria, I agree with Gardyloo and avoid the Clipper. But it is much smaller ship than the other routes, and is said to be a choppier ride in rough waters.

Have a look at the Coho, from Port Angeles. It's a gorgeous route. Or: The Vancouver Swartz Bay route is also pretty, if you were to do a loop for a weekend: drive to Port Angeles, ferry to Victoria, ferry to Vancouver and drive back to Seattle or home. If you are taking your car (which I agree is a good idea) you must get a reservation and come early to line up.

I think it needs mentioned that one negative to Vancouver is that the lines to go through the border are said to be long these days. I don't have current firsthand information but if you go, you'll want to research that.

And reminder: You will need a passport or passport card. And don't forget your phone may have extra charges if you go to Canada so check ahead of time.

https://www.bcferries.com/schedules/mainland/tssw-current.php

https://www.cohoferry.com/The-Route

A fun thing to do would be the Teatro Zinzanni- a dinner show with circus/cabaret entertainment while you are dining. Its a riot. It had to move from it downtown Seattle site to Woodinville Wa.

https://zinzanni.com/seattle/

Since you like bookstores- a few good ones in Bellingham. Fav is village books. That’s at the limit of your range headed north.

time range in general is tricky because of traffic, but you probably know that.

Of things close to Seattle, I like Edmonds and Tacoma.

If you like cultural museums the brand new Nordic Museum in Ballard is one we really enjoy.
https://nordicmuseum.org/