I think the only reason to take a sport coat is if he thinks he would ever get cold in the air conditioning. I took one, but not sure if I ever wore it--except possibly in Apicius, though that venue seems to have changed somewhat. I did wear a sport coat on the country club casual Alaskan cruise on the Mariner when we ate at Signatures, but it wasn't necessary. We're planning a return trip to FP on the PG in February.
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Eugene