I have visited San Francisco many times - and I enjoy mayself each time I've been there. My sister lived in the Bay Area for a few years and we always tried to go to the city by the bay as much as we can.
There is always something to do in San Francisco - it pulses with culture, diversity, and wonderful diversions of an eclectic city. From the city's charming Victorian neighborhoods and trolley cars, to the hip Haight and Ashbury area, to the different ethnic enclaves like Chinatown and Little Saigon, to shopper's delight at Union Square and all of the city's beautiful parks - San Francisco is a tourist playground and a backpacker's delight.
Driving and parking in San Francisco is a headache, so we always tried to take the BART system, the Bay Area's fast and efficient rail system, whenever we can. The last I was there was Spring Break 2004, where a group of friends and I stayed for a weekend at a Hostel and toured the city. Our hostel was located in Little Saigon - a pretty seedy area (be prepared to see a lot of homeless people and shady street corner dealings in SF). But Little Saigon was the place for a great bowl of pho!
Another warning - things can get pretty expensive in SF such as taxis and transportation, so bring comfy shoes to walk and tackle all of their monstrous hills.
My favorite spots in SF are:
1.Chinatown - some amazing deals on Chinese and Asian gifts and other items. ALso, a great place to eat. (The better restaurants are off of the main tourist strip)
2.Union Square - some upscale shopping - but when you're done, eat at Cheesecake factory. Good food with a great view of the city
3. Fisherman's Warf - some fun shops and places to eat by the pier. Bubba Gumps is a fun place to eat. You can also take a ferry to Alcatraz Island from there (something I have yet to do!)
4. Ghiradelli's - The perfect guilty pleasure dessert! The charming sundae shop is located at Ghiradelli's old chocolate factory.
5. Golden Gate State Park - a great place to sit and relax, roller blade or bike ride, or just walk among its rolling green hills. You can also take a special someone on a romantic row boat ride in a man-made lake.
6. Haight and ashbury - immortalized by the hippie generation, Haight and Ashbury has become a hip and trendy place for the younger crowds. Get a tattoo, pierce your tongue, or just go browse among their alternative edge stores.
Other sightseeing spots include the Golden Gate Bridge lookout point and Lombard Street (dubbed the most crookedest street in the world. You'll see what I mean when you see it) There's also great restaurants and a happening night life.
There's something for everyone at SF so check it out!