I'll be visiting DC over Christmas with my 10yo. Our dates are flexible and I'm wondering if the weekend or weekdays would be less crowded? Or is Christmas just going to be crazy all week? Also, can you recommend any particular things that might be fun for a 10yo boy? We're planning on the zoo and the Museum of Natural History already. We'll be staying in Alexandria, so I'd love to hear of anything fun to do there as well. He's not too keen on history yet, but he's really into animals and nature (farm kid.) Thanks!