Going to a park is very fun as it is, but there are some things you could do to make it even more entertaining. Very simple is picknicking, just take some food and drink and go sit in the grass (or on a mat or rug) and enjoy! Something children especially like (though as an adult I love it as well) is a petting zoo. Being able to touch animals, interact with them and perhaps even feeding them is a wonderful experience. You can also make it an educational trip, learning about animals or learning about different plants that grow in the region. In fall, you might be able to collect acorns and chestnuts (picking plants is often not allowed, so be wary of that).
What I like most, though, and what I did today, is the picknicking and talking with my friends. Enjoying eachothers company and the weather and observing the various other people in the park.
What do you enjoy most when going to a park?