For a well lit parking lot, that is guaranteed to have a cluster of empty spaces for everyone to park, check out the rides, and chew the fat, I'd suggest Rose Hill Shopping Center in Thornwood, NY. It's right off of the Saw Mill so it should be easily accessible by all. In the center there is a pizzeria, Chinese, KFC and Deli. but just down the road there are some great bars and more restauranty type places.
I mainly suggest this place due to the parking lot. If you're more concerned about the place to sit inside, the Thornwood Ale House is a decent spot too. I'm just thinking white plains will be too crowded to guarantee we could all park near each other. That's my .02. Let me know if it goes down!