Hike a trail to the top of Buena Vista Park and you'll have a gorgeous view and a chance to burn off the alcohol from all of those Magnolia Pub brews. Buena Vista Park is almost 40 acres with dogs allowed on the trails. (For additional off-leash areas see the Guide to San Francisco Dog Parks.)
The character of Buena Vista Park depends largely on when you're there. Over the years, it's had a bad rap for some of its seedier elements and transient population. The Buena Vista Neighborhood Association has worked to enhance the park and make family-friendly improvements: a playground, resurfacing of the tennis courts.
I've hiked the trails on a crystal weekend morning, when the park is serene and clear. As with any city park, just be aware that the same urban elements exist in both green spaces and on the streets.
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