So what should you wear? As stated above, a smart casual look is perfectly acceptable. Blazers and open sports shirts are good for men, but it's always a good idea to just let your spouse dress you. Women should feel free to wear a demure knee-length dress or a nice pants-suit. Sandals are a definite no-no as it's December, I don't care how cute your feet look in them (our Antipodean cousins might have a little more leeway, but I try not to think about their sartorial escapades.) Also heels over three inches are out. You do not want to meet your Lord and Maker looking like a hooker.