Hi Karen. No problem. As of February, Metro Transit discontinued the bus route from Sea-Tac to Downtown Seattle.
Because of that, I believe light rail is now one of the many public transportation ways (aside from taxis, shuttles, etc.) from the airport to Downtown Seattle.
is a link to some information about the Downtown Seattle Transit Tunnel.
Also, if you decide to stay at the Quality Inn, your best bet is to get off the light rail at the Westlake Station. From there, you have a couple options.
The first is to take the elevator at Westlake Station to the top floor. This will put you on the top floor of the Westlake Center Shopping Mall, where you can grab the Seattle Center Monorail
over to the Seattle Center area, which is where the hotel is located. On their website, they say the hotel is walking distance from the monorail.
This does depend on how much luggage you have. If you feel you have too much luggage, then you can just go to street level at Westlake and try to get a cab to the hotel.
I used to live in the Seattle area, and was just there on vacation (non-cruise) back in June.