My husband and I are visiting Chicago for 5 days in early May and have been deciding where to go for some good food. We are not looking to dine in the most expensive/high end places but do want to eat in some nice restaurants. Some websites describe the dress code as 'Business Casual'....what is this?? Does that mean a suit or would shirt and trousers be alright for a man to wear? I know jeans would be a no-no but what exactly would be ok? Thanks!