The forum will give you some feedback, for sure, on private tutoring. I also hope you give us a call. TPNY is among the best private tutoring in NYC because that is just about all we do (just a couple of other courses commissioned by universities and private companies) and what we've excelled at for many years.

If want to get a top score and feel confident and on on your game: look no further.
If you don't want a one-size-fits-all program: call now.

To echo the above, GMATtix.com has a lot of tutors listed on its site. However, they aren't ranked so there is still that problem. One possible way around this problem is if you find some GMAT tutors that you think you like ask the tutors to talk his two last students. In general when a new student asks to talk to my previous students they (my former students) don't have any problem replying to an e-mail. I think it's good to ask for the two last students they had so they don't just pick and choose students they know will give them great reviews. Although you won't be able to verify they were the exact last two you should be able to tell you that they had classes with him/her recently.

That said, I've heard some good things about the GMATninja in NYC.

Cheers
Dan