Example:
Dear Dr. __________,
I would like to thank you for taking the time for our interview on ______________. I am glad you were able to speak so well of the students and faculty as I am now convinced that _________________ School of Medicine will provide me with the atmosphere I will thrive in. I enjoyed our discussion and found it to be thought provoking. Thank you once again and have a great year!
Sincerely,
memememememememme
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If there was something during the interview I wanted to mention, I would put it in after the first sentence. Also, I try to write a different one for each interviewer following the same ideas as the above.