Time to mosey.
Wander your way to the Haight and pop in to Haight Street Market for some snacks . They do a solid job on sandwiches and picnic fare - cheese, bread, olives - whatever is your jam. Get a bottle of wine (let's be real, get two), then stop in a few doors down at Booksmith for one of the most well-curated selection of books in San Francisco. Their collection spans interesting and obscure subjects with some variety, including stellar staff picks in each category. (For another time, check out their author events calendar too.)
Once you've scooped up something worth a read, keep heading west to Golden Gate Park. Especially if the sun has come out to play, soak it up while sprawled on a blanket in front of the Conservatory of Flowers (easily one of the most beautiful structures in the city) and enjoy your bites and books. Something about this spot and its flora-filled lawn spurs dreamy thoughts and creative juices, especially on sun bleached days. Once you get your fill, stroll down to the De Young. If you're in a museum mood, go get your art on. If you're not, might as well take a trip up to the Observation Deck and get a glimpse of it's killer 360 view.