My nephews and friends are going to visit a friend who moved to Palo Alto last year.
All the boys are very “into” food – both eating and cooking / baking.
They’ll be based in PA, but want to go into SF for a day to explore, and are quite excited about visiting Chinatown (they have experience with New York Chinatown).
Another attraction is regional Indian food in the bay area – they haven’t have been exposed to the kind of specific regional variety that’s available there.
And finally, pizza. They’re curious if there’s a style particular to the area, but aside from that, always in search of Good Pizza (capital G, not plain old good, I was reminded).
For Chinatown, a few places they can wander around and explore over a few hours would be great, including dim sum, bakeries, and anything special to SF. For other things, easy to get to and not too expensive would be helpful (they’re all driving age, but I doubt the hosting parents are going to let them just run amok 
).
Thanks for any recommendations you can throw my way to pass on.