We have a place called Dog's Beach here in San Diego, where the dogs can run free and go in the water, etc. However if we let Daisy or Perry loose they would run with the wind and be in Mexico before we could catch them.
We did visit a Dog Park while vacationing in Palm Springs. There was a larger park for large dogs and within that park was a smaller park for the little dogs. We took Daisy and Perry in there and it did not work out as they wanted to be alpha with every dog in the park, we tried everything to socialize them but they still act like a pack of two. We even took Perry to a dog behaviorist, she said to keep treats with us and when another dog comes along to say nice doggie, nice doggie, and give him a treat.
It doesn't work for him.
We have a big fenced lower yard and we exercise them there or take them to a park during the week on a leash when it's not crowded. I guess there are some dogs who just do not want to socialize and their guardians must be very careful not to subject other people or dogs to their aggresiveness.