I haven't been in concierge but my general opinin on such things is not to bother - you don't spend a lot of time in the room, I'm not sure I would get alot of use out of the services and I think the money would be better spent on other activities (boat rentals, parasailing, tours, great meals etc) That said, if you've got the money then go for it.
My one comment would be to consider the concierege at the Animal Kingdom Lodge as you get the safari benefits which, by all accounts, are amazing.
