I have a free range set up downstairs with a few 7or8' apple trees and plenty of vine hanging from the ceiling, about 8ft off the ground. It has heat lamps, two 48 inch fixtures with a reptisun 10.0 in each to reach farther incase the cham decides to go low, and two hanging drippers that drip into the trees. On the ground I have a three foot tall sanded wooden barrier so that the chameleon cannot leave the area by way of the floor and that keeps them in. Also I have 4 dark green sheets hanging from the ceiling cutting off their view of everyone else so the cannot get huffy and puffy. Once I get my camera working again I will post a picture in this thread so you can see it. The chams love it. It's about 10'x10' in total and heavily planted with the aforementioned trees, plenty of excess schefflera and ficus that are being rotated in and out of cages on a monthly basis, it's like an indoor jungle basically. The best part about it is I didn't have to buy anything for it besides the two UVB bulbs, it's just all my excess plants and supplies. I set it up because my chams did seem to roam without barriers and always ended up going up a whole flight of stairs and sitting by the wood burning stove in the family room or by the window in the kitchen. That gove me quite a scare when I wasn't paying total attention and was feeding my two little males and the big guy disappeared. Everyone of my chams love free range day so I'd say try something out and just keep an eye on them if you let them free range. Good luck.
Justin