Hyland Lake Park in Bloomington, Minnesota has a great playground, and is also known as the Chutes & Ladders Park. Restrooms and concessions are available in the nearby visitor center.
The playground is huge, making it difficult to keep an eye on kids, however the play area is fenced with only one way in and out, which helps. I recommend bringing a change of clothes on hot days because there are misters which will totally soak your kid.
In addition to the playground, we hiked the 2-mile loop around the lake. It's a great hike that I recommend doing before you let your kids loose at the playground.