Haight-Ashbury is two things at once: a 1960s pilgrimage corner that sells its own myth, and a genuinely lovely neighbourhood of painted Victorians on a hill. Walk it for the second and the first comes free.
About three kilometres, best in the afternoon when the shops are open and the light's behind the houses. Start at the famous corner — the street sign, the clock stuck at 4:20 — then head down to Amoeba Music in its old bowling alley, the last great record store, worth a browse whether or not you buy. Detour up Ashbury to number 710, the bay-windowed Victorian where the Grateful Dead lived through the Summer of Love; it's a private home now, so admire from the kerb.
Then the climb. Buena Vista Park is the city's oldest, a steep green slope of old cypress where the drainage stones are salvaged Victorian gravestones, laid edge-up if you look. The summit gives you downtown, the bay, the bridge. Come down the east side and walk the grander Victorian blocks toward Alamo Square, with the 7 bus from Fillmore to carry you on.