I'm making my first trip to Nantucket for a friend's wedding on Oct. 1 and am looking for a few recommendations. Are there places that absolutely cannot be missed? I'd like to fit in some great seafood and a place with a very typical Nantucket atmosphere where I can take my parents, who are from Chicago and generally prefer a more laid back, unpretentious atmosphere. Also, the reception is in the afternoon, so any suggestions on a bar to go to in town after the wedding would also be appreciated. Lastly, should I be worried that places will already have closed for the season?