Quail Cove Park in West Des Moines has a playground, rope climber, swings and a basketball court. There's a parking lot, picnic shelter and restrooms (open April 15 - October 15). In addition, there's a half-mile dirt hiking trail that loops around the park.
We hiked with Muddy Boots Forest Camp today. Their Boots and Books program is great. It includes a hike, snack, story time and each kid gets to choose a book to take home at the end.