From the website, it looks like the EMP(Experienc Music Project) is open.  (See post #14).  I would suspect the Space Needle is open too.

 I'm sure you'd rather be home Beagle. Two 4.5 hour nappys back to back and it's over...or you could do what Old55 says. And theres always the CH.
 
 I'll be away...what's that I hear? A collective sigh of relief?  Have a good weekend guys!

EMP and Museum of Flight are both open on Sunday. So's the waterfront (good eats!) and Seattle Center (EMP, Space Needle, Science Center,  glass museum, more eats, all in one place).

Hi,
 
If you get bored, you can always drive down 3 hours, and you can visit moi in Vancouver, Craig in Portland (if he stops playing incognito for 10 minutes!) ... not that it makes any difference, but I can at least buy you a dinner just for the pleasure of finding out that there are some REAL folks in the CH, instead of ________________________________________________!

I would like to visit Vancouver, but probably not going to happen this trip, Pedro!
 
Those would certainly fill the day Dave!  that's what I'll probably shoot for!