If you're putting a leash on your kids on a public place like the mall, carnival, or theme parks, you're admitting to yourself that you could not take care of your kids. Kids are supposed to have fun. They need their freedom to enjoy, especially if it is a theme park.
If you really want to have fun with your kids give them space and try to play with so that you won't have to put on that leash. Or you can just try to hold their hands while walking and viewing the park. It is much more intimate and gives you more bonding with your kids. If it is really that bad that your kid always run around like my kid well there are other ways to keep an eye of them kids. One gadget that I have found is this tracking device, it is called the Here I am Kid Tracking Device. They made it look like a toy so that your kids wouldn't just throw it away but just to make sure clip it to their clothes or put it in their pockets if going to the mall, parks, or public places. If you noticed that your kids are no longer around or no where in site just click the key chain transmitter and you will hear the bear beep. It also alarms you if your kids had gone off the 25 feet radius. Pretty neat gadgets and you don't have to make your kids look like a dog. I know there are something like this that are already available in the local markets or you can visit some gadget shops. Just remember your kids are not dogs so don't put any leash on them.