the thing is....in both of my interviews, the interviewers didn't give me their names. oh well, if you know their names, you can do that...but if you don't, it shouldn't hurt your chances.
the first few schools I interviewed with I sent real thank you cards.....no replies.
then i started to email them with a thank you note and some people wrote back. i find the email much more convenient and you get more replies (in my case). Or maybe it's because i used the extra thank you cards from my wedding (a little feminine... )