There's a pay lot across from Powerhouse Park, and limited metered spaces around 15th Street and Coast Boulevard. For free parking, you can cruise the narrow streets north of 17th Street, but in summer it's near impossible to find a space. South of 17th Street, leashed dogs permitted all year long. During non-summer months, mostly locals, walking, jogging or surfing. In summer, a mix of surfers, families, high school kids and tourists.
Families tend to congregate near the parks.
Best bet is to spread a blanket on the lush lawns of Seagrove Park. Main lifeguard station is at 17th Street.