When Golden Gate Park is full or a tournament holds sway over your usual tennis court, try one of the several little-used public gems scattered throughout the Presidio. Julius Kahn Playground, on West Pacific Avenue at Spruce Street, offers several courts just inside the southern border of the Presidio; if folks are playing on these, head deeper into the park and search out the single court at Lombard Street and Letterman Drive. There's another on Moraga Avenue, across from the Visitor Center, where you can also get a map and ask one of the friendly guides to highlight the tennis courts (there are a few at Mountain Lake Park not far from the Park Presidio Boulevard entrance). You can't make reservations at any of these spots, but you usually won't need them -- even on a sunny weekend day.