Carlisle or Nats-which is better?

It just depends on why you are going. The Nats is definitely the place if you want to drag race. Having been to both, Carlisle is much bigger, particularly with the huge swap meet area. If you are looking for hard to find parts or even a car, Carlisle is the place to go. I like the Nats just fine, but I am partial to Carlisle myself.