我觉得如果你发email就都发email,发thank you card就都发thank you card, 不要搞什么一般的staff就这样，主要得就那样。做什么事都应该一视同仁。

我收到过老美写的thank card和email，主要就是感谢这个opportunity，对这个position很感兴趣，再说1-2点你们interview的high points.

Good luck!

Thank you letter is just a formality. E-mail is fine. No need to send the card. Should treat everybody exactly the same.