Hi Moe - you really want to have live plants in there as well. Live plants serve other purposes than decoration....they help to keep the humidity up better than fake plants, and they provide a more natural source of coverage. I used to have the same problem with ficus so what I do is switch my plants around. I have a tall ficus and a large schefellera. I rotate them in the cage about every3 months I take one out and put the other in. Mine don't seem to loose as many leaves anymore.
I would use fake plants to fill in around the edges or bridging between two branches like a vine. - Scrappy