I wouldn't wear a suit, but that's just me. I feel for something like that it comes off a bit too try hard. There's nothing wrong with showing you're interesting and dressing respectfully but if the consensus is wear a suit, then wear a suit. If it was me, I would wear a pair of slim cut black cotton twill pants, a cute and interesting flat (or heels, whichever you prefer) and a shirt (I have a cute white sleeveless one by Rodarte at the Gap from their 'white shirt' collaboration with the CFDA nominees that is basic but has interesting pleating) or a dress shirt. It has just occured to me that maybe you are not female, so if you are male, I would just wear a simple khaki's/dress pants and a button down with a decent shoe. Pretty straight forward and basic. It's Vanderbilt in the summer. I don't think they expect you to wear a hot and heavy cotton/wool blend suit to impress them. The most important thing (other than looking half decent) is being comfortable. If you're uncomfortable with what you're wearing, that will come across and you won't be at ease and engaged.
Trust me, if you are a guy wear at least a sport coat and tie. It is summer time in Tennessee so wear a light colored suit if possible. Anyone who tells you to dress down either:a) wants your spotb) is socially retarded like many law school studentsThis is not a Saturday afternoon Yankee game, a weekend at the beach or a night out at a college bar with your friends. You are not going to make a bad impression dressing up.