When we first moved to Memphis, I had told my wife about Mud Island, after I found it on the Internet. For the first several weeks, she kind of blew me off, as she didn’t think the kids would be interested. Finally, after about a month of pestering, we went to Mud Island. Wow, was it fun! Not only did the kids have fun, but my wife told me that she wished she had done it before.
How to see Mud Island: We found parking in a nearby garage, and walked about ½ block to the entrance. If you have small children, bring a stroller even if you don’t use it—there is fairly heavy traffic, and you’ll find it convenient. Entry is free, although you can pay to use the monorail system. Again, having the stroller means that you can walk back after your kids crash. We walked to the park, which is right on the Mississippi River, and actually contains a scaled model of the river itself. Our kids had fun walking up & down the river, while we entertained ourselves by reading the information signs. If you start at the head of the river (actually several different sources), it can take you at least an hour to leisurely make your way to the Gulf of Mexico, where you can eat at a restaurant, play in the pool, or rent paddleboats in the “Gulf” itself.
Overall: Cheap & fun, Mud Island gets my vote for families with young children. Easily reachable from I-240, you can do this in a morning or afternoon.