We did Epcot 2 years ago on TGiving and are going again this year. We usually do school breaks and while Spring Break usually by crowd level ratings is "lower", we didn't feel a huge difference between that and Tgiving. I think the answer is that yes, the resort is very crowded and so if you are used to "dead" times it will feel different, but if you're used to school breaks or summer crowds, just have to manage as always, and the weather being what it is for TGiving (so mild and comfortable comparably) I think helps.