When most people come to San Francisco, they stay downtown, either by the shopping or in Nob Hill with all the views. It makes sense, really. There are gorgeous hotels, and the location is perfectly central with public transportation taking you to every area of the city you'd like to visit!
It's the home of the flagship Gap and Banana Republics, H&M, Zara, Madewell, Uniqlo, Anthropologie, Urban, all the higher end stores, so there is endless shopping to be done, if that's what you like.
People are always asking where to eat around there and it's probably the hardest area of the city for me to recommend. For breakfast, Sears Fine Food or Dottie's True Blue Cafe, for sure. For lunch, it sounds strange, but the food court at the Westfield Mall has REALLY good food, good deals, and good variety. My personal favorite is Coriander Thai (downstairs), where we can get basil chicken, red curry, and pad thai for three hungry girls for $12. S likes it because they have mini clean potties there for tiny kids. TMI? Hope not. On the top level, there's La Boulange if you just want a snack or coffee- see HERE- and the prettiest ceiling ever. You also could go to the Nordstrom cafe at the top of San Francisco Center and check out the view up Powell Street, and enjoy good eats.
Dinner is the hardest. We almost never eat dinner downtown except when we've gone to Morton's for work dinners or something. My best recommendation is to take a little walk more toward the financial area, and there's a little alley there called Belden Place. It has the charm and romance and some solid Italian food options and it's not too far away.
If you like to be pampered, I one time got to have a spa day at the Nob Hill Spa at the Huntington Hotel, and it has to be one of the best spas EVER. There is a swimming pool with glass windows in the spa, where you can order food and gaze at the most gorgeous views in the world. Totally unforgettable.
If you're like me, with kids I'd say you MUST hang at Union Square for a bit and grab a coffee or something and enjoy the sun and people watching and let the kiddos run around- and you must also take a cable car. The kids LOVE cable cars. I remember thinking they were the best when I was a kid, and Sophie still remembers and talks about the one time we took a cable car too. It's really really really fun.