Does it make sense to email a thank you to your interviewers in addition to sending them a thank you note via snail mail? I wasn't sure if this would be considered redundant if you are going to state similar things on paper.
I agree with you that two thank yous would be redundant. A snail-mail note is more formal, and more likely to be given individual attention than an e-mail that is in the midst of twenty others and would be quickly deleted. Save the email for a question you might have so you can get a prompt response.
I agree that duplication is overkill. I only duplicated once, with a student interviewer, because I wasn't sure if her address listed on the school's directory was still current.
But I'm still really unsure about whether snail mail or email is better. I always felt more comfortable with handwritten snail mail letters--I agree with the PP that it seems more formal, and demonstrates more effort.
But I've also wondered if email might be better in cases where you know the ADCOM is going to meet shortly after your interview or the interviewer is going to write the evaluation ASAP. If that's the case, it makes sense to me to email, so that the interviewer has your enthusiasm for the school in mind as they write your evaluation.
Of course, when I was interviewing for law firm jobs, one interviewer told me he was really impressed when he saw the postmark on one interviewee's handwritten thank you letter--it was postmarked the same city as the firm was located in, even though the interviewee was OOS. That meant the interviewee wrote the thank you promptly and deposited it in a local mailbox before he took his return flight home. The interviewer said he was really impressed by that promptness.
Sending an email and snail mail is over kill. If I was an interviewer I'd almost see your thank you as being less sincere if you made obnoxious attempts to grab my attention and force a thank you down my throat. Keep it simple and send a short email pointing out what you enjoyed about the interview. No need to send cakes, but Im sure some of you out there do...
I sent thank-you e-mails to all three interviewers at Pitt the day after, and included some follow-up comments on the things we talked about (e.g., restaurants here in town (for my non-local MS1 interviewer) and book recommendations (for my faculty interviewer)). I sent a paper general update letter to be included in my file covering the things not included on my AMCAS app. Take this FWIW.