Congrats on the interview, Nygirl. Here's what I remember from my vist.
There was a shuttle that runs back and forth between Davis and Sacto, maybe every half an hour. I didn't take it, nor did any of the other interviewees that day, but that was just cuz we had cars. Are you going to be flying there? It took about 20-25 mins. to drive without bad traffic in the afternoon, depending how much you like to speed. If I remember correctly, to make it on a shuttle, you have to leave around 45 minutes before the time you want to be there. Like, to get there at 2, you'd get on a 1:15 shuttle. Oh yeah, if you were driving to Sacto, which I don't think you are, you also have to worry about parking, so factor in another 10 mins. for that. They give you a permit to park in the big structure adjacent to the medical center, but the problem was that the structure was very very full as I looked for parking, and as a result, I was late and panicky for my interview. Luckily, the interviewer was late.
They didn't offer student hosts, but just a list of local motels around Davis and also around the medical center. I only investigated the motels around Davis.
If you have a 9:15 interview, it seems like you wouldn't have much time to spend at Davis. They have a welcome sessions at 8 am by the director of admissions, but you really could only stay for maybe 20 mins of that, depending on the shuttle schedule. You should probably call or email Terri Hall to ask her what she suggests. Maybe you can go straight to Sacramento in the morning, and after that, head over to Davis for your student interview at noon? You probably will miss the tour of the Davis campus too because of your interview schedue, but that's not a big deal.