While it may be a far better position (anywhere at Mayo), I strongly suggest that you go to the interview at the nursing home. #1, it will be practice that you will need in the interview process. Especially if you're interviewing somewhere like Mayo, where the competition is going to be HUGE. You'll be able to get an idea of what things will be asked and be able to polish up your communication skills. And from what I'm seeing, Mayo is not a 100% sure thing. It may be a strong lead, but it's not always going to be a 100% lock.
An example...When my job goes away where I'm at, my preference would be to land at 3M. My dad worked there, I have friends that work there, but I'm not counting on it being the place that I will definitely end up. I'm going to look elsewhere and take interviews at other places.
Some tips from someone who's been on both sides of the interview: You have to look at it like you are interviewing them just as much as they are interviewing you. Be yourself, and don't pretend to be someone you're not. There's nothing more frustrating as an employer for someone to not be anything they were like when they start, compared to when they interviewed. If you have to be someone else to get the job, you're not going to be happy, and it'll end up badly. Ask them questions; that will tell the interviewer that you are an active participant in the interview, and not just there to take everything that they throw at you. Just my
Good luck!