I'd recommend the northend, for sure. Just walking up and down the street is exciting. Lots of tourists, but lots more locals and regulars, because it's win-win for everybody. There are dozens of great choices, and the rest are still quite good.
Bricco's and Lucia's are my favorites, but regardless of which one you pick, follow it up with a visit to Mike's Pastry Shop! (I'm not even a big pastry fan, but you become one when you go there, as you are overwhelmed by the array.)