Jesus, 2 acres would be amazing. The park I ride is maybe half an acre, something like that.

It would be good to have different sizes of the regular stuff, a small and big bowl, various sizes of quarters and half pipes, and various size rails, plus some good banks and ledges. Most important thing: shade. It sucks to have to sit in the dirt under the hot metal halfpipes to rest, make a sheltered thing. Look at pictures of other skateparks to get ideas.