Addenbrooke Park is a large grassy park in the middle of Lakewood, CO. Our girls love the playground there (especially the tire swing!) and there's plenty of tables for a picnic. The pavilions offer shelter to get out of a sudden rainstorm and can be reserved for get-togethers. There's also a large pond to wander around with lots of geese and a few ducks to watch.
A bit of trivia...this park is also home to a bronze sculpture called "Snapshot" showing of Michael Jackson and friends together as children, crafted by local artist Jane DeDecker and commissioned by Jackson himself in 1992. Read more at http://www.denverpost.com/entertainment/ci_12717724