Sorry to say, my choice of classic paintings is limited. I am perhaps most impressed with The Wedding Feast at Cana as I saw it at the Louvre on a trip back when we could still travel. It is about 20 ft b 30 feet in size, and you can immerse yourself in the scene. At the time, it was in the same hall at the opposite end from the Mona Lisa.
Usually, I get my classical painting education from the That is Priceless comic strip, which pairs classical paintings with humorous captions. Caution, as some are a little risqué.
http://thatispriceless.blogspot.com