When we lived in the city (Denver), I found people were friendlier, because we would often see each other as people often walked places, because there were actually places to walk to. Our next door neighbors had 4 kids, and one of them would sometimes come over and play with the dogs.

Now we live in a large suburb of Denver because the suburbs were the only place we could afford to buy a house. I love our house, but I don't like living in the suburbs. I don't know any of the neighbors- we smile and say "hello" if we see each other but that's it. I think it's because people use their cars to get everywhere, and everyone has a really big back yard (which is really nice, I like having a large yard) but if you are outside, you don't really need to see or interact with anyone else.