Northgate Community Park in Fremont is a great park for all ages.
There is both a smaller toddler playground and a larger playground for older kids. They also have swings, a basketball court, cricket fields, two baseball fields, several picnic tables, a few benches, BBQ's, and bathrooms.
There is also a nice, paved sidewalk that runs around the park that is perfect for bike and scooter riding and walking. You will find plenty of parking in the parking lot or on the street.
Northgate Community Park is located at 34060 Rowland Drive in Fremont.