I really wanted to write a rave review, but can't even come close. I will be honest about my personal bias in some matters for which Celebrity has little or no responsibility, so that readers can sort out what's relevant to them.
We arrived the day before departure, and stayed at the Inn at the Market in Seattle. Lovely inn with helpful staff, across the street from the Pike Place Market, and within easy walking distance of several restaurants and shops.
Took a cab to the pier at about 1PM, where the Very Long Check In began. Got in the first line to have our bags scanned and dropped off (15 minutes), got in the next line to go up the escalator (about 30 minutes), got in another line to go through security (10 minutes), and were sorted into yet another line to be checked into our cabin. Fortunately for us, the concierge class had a very short line and we had to wait just a few minutes to see an agent for our cabin. The non-concierge passengers were herded into a zig-zagging queue that had to be several-hundred-persons long, and reminded me of Ellis Island. Even the Captains Club line had several dozen people I felt profoundly lucky. Once checked in, we ordered into another line to get our picture taken, which we quickly dodged, to get into another line to the gangway to get on the ship.