This could be known as the summer of splash pads since so many different ones! It was a warm summer, and the kids are at the ages they love to run and play, so splash pads are perfect! You can go if you have 30 minutes or 3 hours, plus they're free!
Des Moines recently added a beautiful one at Cowles Commons downtown. We went there three or four times. This was a Tuesday night while Adam and Mark were practicing and the kids didn't want to be quiet ;)