As I recall the 2nd "formal" night is either the next to last night or the night before that. Toward the end but not the very last night. I've been on the Spirit in both Alaska and Mexico and have eaten at the Supper Club both times. By ALL means do it. It's worth every penny and more! The service, the ambiance, the presentation is fantastic. At first I thought, well the dining room dinner is fine, why pay extra, but I was encouraged to go to the Supper Club and it was more than worth it.