Good Places to Play in the Winter

Everyone knows that summer tennis is great. It's easy to find an outdoor court almost anywhere you are in and around the Philadelphia area and getting on the courts is just a matter of sitting & waiting for people to finish. I live in center city, 20th and Pine and there are tennis courts just 5 or so blocks from me that rarely have more than a 20 minute wait to get on. The winter brings a different story. Finding available tennis courts is much more difficult, especially if you are not part of a recurring game & just want to pick up and play sometimes. I would love to share premium places or maybe hidden gems to play tennis.