Planning on coming to DC thanksgiving weekend. Is it a bad time to visit museums?
no, why would it be.
Thanksgiving Day the museums and other sites are generally open and uncrowded.
The day after they may be very busy as lots of locals have visitors in town. Everyone has been cooped up in the house the day before, so they look for something to do.
Needless to say, "lets go to the museums" is s popular choice.
If you are there for the weekend you will be able to see some of the museums.
Today (Wed.) is great for the museums. I just got back. No crowds at all, and plenty of parking (though only for 2 hours at a time.)