We like Elm Ridge Park in Rocky Hill. It's on Route 160/Elm St. There is a great park called Addison Park in Glastonbury. It's at the intersection of Addison Park and Great Swamp Rd in Glastonbury.
Instead of playgrounds, some other good seasonal things right now include Lyman Orchards, Old Wethersfield main street of scarecrows and Pumpkintown in East Hampton.
If you had a membership to Kid City, it is also good at 5 other children's museums in CT. They are:
Children's Museum of Southeastern Connecticut (Niantic)
Imagine Nation Children's Museum (Bristol)
Lutz Children's Museum (Manchester)
The Children's Museum (West Hartford)
Stepping Stones Museum for Children (Norwalk)
Imagine Nation and The Children's Museum in W. Hartford are geared a little older than toddler, but I have been there with my 4 yr old and 2 yr old and they still get something out of it. Lutz is small, but has animals and a running train that my son loves. Give them a try...they might be an extra 20 minutes or so, but they're different.