<p>Kosuke--It's never too late to thank someone for a college interview. You might even consider alluding to it in your message, e.g., "I continue to feel as enthusiastic, if not more so, about Pomona as I did when I spoke with you." Perhaps you can say how your conversation with your interviewer led you to discover <em>additional</em> appealing aspects about Pomona that excite you about going to college in general and to Pomona in particular. Here's your opportunity to shine! </p>
<p>As to clothing for upcoming interviews, how about corduroys? An alum interviewer my D had actually mentioned that she didn't have to dress up because they were meeting in a Starbuck's. Business casual is how one would describe it in a working environment--clean, non-grungy clothing that you might wear to impress someone on a date. Think first impressions.</p>
<p>Good luck!</p>