For an extra 2500 points per night you can reserve a Grand Luxe Room (which I believe is two grades higher than the standard room). You have to call SPG since the website doesn't show this. The Grand Luxe Room has a small seating area and his/her sinks in the bathroom. Feels like a small suite. They may still upgrade you to an Astor or Madison if available.

I surprised my wife with the St. Regis last year at Christmas time (she thought we were at the W on Lexington). She still talks about it. Definitely worth the splurge at least once in your life. And you can't beat the location.