I've only had one interview weekend so far, but my best advice is to try to match and feed off of your interviewer's energy. I agree that the "personality check" is definitely a big component of the interview, but I think your general vibe is more important than working in any particular content about your hobbies or personal experiences, unless that comes up naturally. My advice is to be as open and positive as possible. If you're nervous, make sure to correct for that as much as possible in your posture and face. Good eye contact, smiles, confidence, and calm, non-rushed answers can go a really long way I think. The interviewer is trying to assess whether you are competent enough to succeed and whether you're a good fit socially. If you can come in and speak confidently and appear at ease, they'll be convinced of those things.
Also, one of my biggest tips is to look up anyone you're interviewing with on Twitter and see if they've (re)tweeted any interview tips. Several of my profs have done so and it can be really advantageous to read to get a better sense of what they're looking for and what questions they're likely to ask. Be prepared!