DR Danise - Yes, the Fall is quite a "heavy traffic" period in NYC, and the hotel rates start their creep to their Thanksgiving-Christmas peak. Lots of fashion stuff, lots of shopping stuff, etc.
I'd say book now if you can just to secure some sort of decent rate. And, usually, this far out, you can still have the option to cancel the reservation without penalty later on. Were you checking the rates directly with the Muse? or via some travel site? I'd say check with the Muse directly, just in case... you never know.