Is Upper East Side in New York City a good place to live for families with kids?

Yes. Most people that want to stay in Manhattan move to the Upper East and West Sides. It's a very family heavy area. To be honest, I would rather live on the Upper West Side if I went uptown with kids. It's prettier and not as stuffy. There are beautiful parts of the Upper East Side such as Sutton Place, but the Upper West has more trees and more of a neighborhood feel, in general. But, all of the good private schools are on the Upper East Side and there are definitely a lot of kids, so if you plan on living there, it's not bad by any means.