I only have one neighbor, but I used to hang out with them all the time when I was younger. Now I don't so much anymore that I am in college, but I always make a point to talk to them when I am home. (they are older and married with no children) But I still house sit for them when they are on vacations, and maybe once or 2x a year we do something more with them.
I'm moving in a few months to DE, and the apt complex I hope to get into I know one of the couples, but I am not sure how much interaction you see in people in the situation.