Since James' answer was correct, ill just throw some input out there. At my day job (ATC) we used to be required to wear "business casual attire." Starting about 1.5 years ago with our new contract all that is required is "neat and clean." I think some people in the building take it a little far on both ends ie: some still keep up the biz cas, and some wear hat and flip flops. Personally in most lines of work, I want the person "working" to be working comfortably. I don't think that the business casual attire affected me that much when we had the dress code, but now that we can wear more comfortable clothes, I think it just makes everything that much easier. Now after all of that mumbling I have worn some comfortable polos before. Check out target, the polos they have are made out of that "soft style cotton." I don't know the real name for the fabric, after all I am a guy.