I'm assuming you're staying in those hotels because you're using points or have some great deal, right? Especially with the Southcenter location, you're going to be spending a long time in transit every day with public transport. You'll have a 15-20 min. walk from the hotel to the nearest bus stop where you can catch a bus downtown, or else take the hotel's shuttle to the airport and catch the light rail from the airport to downtown. Either way you're probably looking at an hour or more in each direction. The airport Doubletree is better located; it's a shorter walk from the airport light rail station, so if there's any way you can stay the whole time there, it will be a lot more convenient.
There's plenty to do in the winter around here. The ferries are fun, the downtown area and many of the neighborhoods are full of action, and nobody's going to force you to hit museums, although I will recommend two - the Museum of History and Industry located on Lake Union in the downtown/Amazonia area, and the Museum of Flight, located on Boeing Field roughly halfway between Seatac and downtown Seattle.
https://mohai.org/ and
Home | The Museum of Flight
For music and activities, check out the Stranger -
https://www.thestranger.com/ - for its listing of venues and events.
Public transit route planner -
https://m.tripplanner.kingcounty.gov/