What are you interested in? As a SF resident of over 25 years and a native of the Bay Area I can make a few recommendations, but there is plenty to do in just five days. I'm big on walking tours; if you want to see a city walk its streets. Start out at the Grant street entrance to Chinatown (at Bush) and walk north on Grant to Broadway. You can browse the shops and get a flavor of old Chinatown. At Broadway you get into North Beach and some great shops. If you're interested in literary history, make sure you stop at
City Lights bookstore (founded by Beat poet Lawrence Ferlinghetti) on Columbus near Broadway. Continuing on Grant north of Broadway you get into some of the old Italian area of town. From there it is a steep climb up to Coit Tower on Telegraph Hill. Inside the tower are some great old '30s era murals that are worth the time to see. The view from atop the hill is great as well.
If you're into the tourist stops then take a Cable Car over to the Wharf - I like the ride on the Hyde Street car on a clear night - and it drops you off at the old historic piers if you're interested in maritime history. From there it is a short walk through
Ghiradelli Square (the chocolate factory is a must for the sweet tooth) to Fisherman's Wharf. If pocketbook permits try
Scoma's,
Sabella's, or
Alioto's. There are better restaurants in the City, but these are old time Fisherman's Wharf places that give you a feel of what it once was like. On the other end of Fisherman's Wharf is Pier 39, which is a tourist trap - kinda fun, but little to do with Old San Francisco. The best part of Pier 39 is all the seals and sea lions that like to bask on the pier and bark at tourists.
To the south and west is the Haight. Walking from Haight and Masonic to Haight and Stanyan will give you a feel of the old 60s. Just be sure not to breath to deeply if you have to pass a drug test for work. South of the Haight is the Castro District, a largely Gay neighborhood, that has the wonderful
Castro Theatre.
Too long for walking is a beautiful drive through the
Presidio and down to the
Cliff House and to the Sutro Baths and Beaches.
San Francisco is a great city of amazing neighborhoods and I've just scratched the surface of what is available. Plus there are great destinations in the surrounding area - Muir Woods, the Napa Valley, etc. If you want more tips feel free to ask, either here or send a pm.