Agreeing with this. I used I81 to get to my son's college in Virginia. While I81 is less traveled than 95 and is generally your best option, it is FULL of tractor trailers, it's 2 lanes, and those trucks are rolling. There are many accidents. And because it is 2 lanes, it can be pretty bad when one happens because it often results in a complete shutdown. I don't think it's going to be great on the day before Thanksgiving but maybe better than I95.
I will say that traffic patterns on I95 have changed somewhat over the years. The Wednesday before Thanksgiving was always the big getaway day. I work in DC and live south in Virginia. I always dreaded my commute home that day. What I've found is that people are "getting away" earlier and earlier in the week and Wednesdays over the years have been a breeze actually. Not to say there isn't any traffic but, it has been better. What I can say is that if you choose 95, if you have an EZPass, once you get through Maryland and it's past 10AM, you can take the toll lanes all the way down close to Stafford, VA with an EZPass. If you have 3 people in your car and an EZPass flex, it won't cost you a dime. You'll then just have to deal Fredericksburg to Richmond which could be tough.
But I agree with the poster I quoted above: I think traveling that day is going to be difficult and if you can drive at night that would be a great help.