Here’s where you’ll find some of the nicest Little League baseball facilities in the San Francisco Bay Area including six baseball diamonds & an enclosed batting practice area. Sea Cloud Park also has some soccer fields and is a good place to start a bike ride along the San Francisco Bay Trail. http://www.fostercityfun.com/san-francisco-bay-trail-levee-pedway/#map
Great stretch of the bay trail for biking/walking/running. There are always lots of people out. Great views of the bay.
This section of the bay trail extends as far north as SFO airport and as far south as San Bruno Airport. I biked this trail then headed south and did Redwood Shores Loop all in one bike ride for 23 miles total.
The start/end point is in the parking lot of an apartment complex - I suggested an edit.