I would say that while a suit is not required, nor expected, if you have one, then I would recommend wearing it. A suit will not make or break the interview, but I would think if there were two equal candidates, that there could be a slight edge to the candidate who made the extra effort. We bought both of our kids a suit to wear for their senior years. They both got a lot of use out of them with various civilian and A/NROTC scholarship interviews, congressional interviews, formal scholarship awards ceremonies and our son even wore his to the Prom. Even with DS being a cadet now at USMA, and our daughter a NROTC Midshipman, they have both still had occasions to wear these suits. In my opinion they were a good investment and I figure they might as well put their absolute best foot forward.