The rooms in the Mediterranean Inn are carpeted. For some reason I'm remembering wooden floors at the MarQueen, but I could be imagining things. pherank, do you remember?
If you end up in a central downtown hotel, you can take the monorail back and forth to Seattle Center, unless you want a late night, and then it's a short cab ride or a bus. Based on what the Metro website says, despite 151,000 hours of service being dropped on 27 September, none of the impacted bus routes go from downtown to Seattle Center, and I don't see any cuts for LINK, the light rail that goes from the airport to downtown Seattle.
Just know, if you haven't used light rail, it's at least a 1k walk through the north end airport parking garage to the machines where you buy a ticket, and then up the escalators to the platform. If your plane lands on the south side of the airport -- international or A gates -- it's another almost 1k walk through the airport to get to the north end to start the trek to through the parking garage. They decided everyone should have to do this, and killed the buses that ran from the south end of the airport to downtown, one of which was an express bus up I-5. From downtown to Seattle Center, if you're staying at the Mediterranean Inn, the MarQueen, or the Maxwell you can take the D Rapid Transit bus to Republican stop (for the Mediterranean Inn) or the Mercer stop for the other two, and you'll be within a block of all but the Maxwell, which is another four or five blocks from either the Seattle Center West buses (D Rapid Transit, 1, 2) or the Seattle Center East buses (3, 4, ask the driver for the stop). For the Sheraton Four Points, you'll want the Seattle Center East buses, or you'll be rolling your suitcase for a while (but at least mostly downhill).
Whether you take a bus to Seattle Center or the monorail, you have to come up from the bus tunnel at Westlake (end stop) and come to the surface. The buses are on 3rd Avenue (walk to mountains and water, away from Nordstroms). The monorail is at Westlake Center. You can take the escalators through the Center or the elevators from the southwest corner of Westlake Center.
The monorail will leave you a equidistant from all three hotels, but it will be a uphill incline to get to any of them.
You can't use a bus transfer on LINK light rail. I'm not sure if this is true the other way around.