Is Washington Heights in New York City a good place to live for singles?

No. And, to be honest, I wouldn't recommend the neighborhood to anyone moving into New York. If you are coming to live in New York, you should live where New York is alive. Washington Heights is not that place. The bar and restaurant scene is minimal if anything, transportation is the pits and not one person you know and become friends with will live anywhere close to Washington Heights -- I promise you that. It's pretty isolated and not fun at all.