Challenge Park looks mint!
From what I've seen from the web site and streaming video from warpig, Challenge Park has to be the ultimate paintball park. I think the only htink that looks missing (correct me if I'm wrong) but a hyperball arena like the one at SC Village.
But in the end you need tree's, not pure forest, that's a bit boring. You need barracades and huts, barrels etc like cat campaign on surry. A combination of them all would be great, with perhaps a bar and brothel for good measure.