I would start to look at areas near your hospital, because getting around the city takes more time than you think (my friend lives four miles away and it takes me 20+ minutes to get over to her via car). There are so many wonderful areas to live in, but by your age and description, it sounds like you might like: the Marina, Cow Hollow, parts of SoMa, maybe even Hayes Valley. I live in Noe Valley, and while it's "cute", it's not "hip", unless you're a new mom, then it is quite so. It's off the J- Church muni line though, which is a nice convenience. PM me if you'd like more info, privately! You'll love it here!