West Portal Playground is perched above the West Portal Muni stop, where the K, L, and M lines enter the underground system.
It’s got some nice playstructures for younger kids (bigger than toddler), and also has a nice and (for San Francisco, relatively) level grass field which is great for soccer, frisbee, catch, or whatever free-form sport you are inspired to play.
There is a community building and restrooms at the playground, as well as several picnic tables.
Weather: We were there on a perfect day, but it can be a bit cloudy on this part of town. Unless it is a spectacular day, I’d suggest you bring a light jacket (or two)!