There is a lake for fishing, a wading pool, plenty of shelters for picnics and great places for spreading a blanket and having old fashioned picnic. This park is huge and is a great place to stop, picnic lunch, and run off some steam before getting back in the car.
Emporia is literally on I-35 so access to the highway is simple and easy. Its a college town, so if you aren't the "pack a cooler" type you can swing by the numerous fast food choices or grocery store to pick up lunch and take to the park.
There are events during the summer, the best being the Mid Summer Fair if you're going to spend the night. There are a ton of hotels now between the college and Industrial Rd.