The best deal I got was for a Hummer H2 on the Big Island Hawaii. They wanted something like $300+ / day. 1 week came to ~$3,200 all in, but I used 5,000 points instead.

Here are some photos (about 1/2 way down the page) We drove it all over the island. Lots of fun.

I pretty much save my points to use only for 1 week non-peak prestige awards and only if the car is over $100 / day or more. I have to think about it otherwise.

The 200 point weekend day awards are also a great deal, though I don't think you can use those in NYC and they only do the special occasionally.