I haven't sent one thank you note yet. I have no reason to thank the school unless they pay for my flight/drive/lunch etc. And even schools like USC, who give a free lunch, charge $80 for a secondary, so really I think a call girl is more in order.
Let's stop being sodomized in this process and take control. They should be thanking us for putting up with this whole stressful process. It should be etiquette for interviewers to thank the interviewees for being interested in their school.
Unless, of course, you really connected with an interviewer - then stay in touch 'cause you like the person. Or if somebody let you stay in their room for a night so you could save on a hotel - thank them. Forget the freakin' interviewer. Most medical students interview applicants to put it on their resume or because they like having some power over a poor kid's life (most likely the first reason).
Love,
Jaded