DR Esteemed BK - The rate quoted to you by the Doubletree sounds about right for this time of year. And since you'll be coming in for a weekend too...
As other readers have posted, your best bet may be some of those discount travel sites. Alas, you may also have to pay for your room up front, but if that's what you have to do, that's what you have to do. I've checked into some of those sites, but I've usually gotten a better rate just by calling the hotel directly - not the hotel chain's reservation line, but the hotel itself. -And since you are your own business, I'm sure you could also qualify for some sort of corporate rate.
-Of course, it's sort of "funny" - December is actually the highest nightly rate period for most of the hotels in NYC. -And unlike some "working" cities, the rates actually go up on the weekends. -But, come January 3rd, the rates for most hotels drop to next to nothing! I still remember booking a room at the Omni Berkshire Place for only $110/night which had been booking at $525/night during the holiday season.
I'll be in the middle of techs and rehearsal for Hallelujah, Baby during that time, but I may be able to make it up there that Monday. We'll see...
-There's also a nice mystery bookstore or two in DC...