Eugene,
You're correct. The "old" Regent website showed the second and second to the last nights of Grand Prix to be formal optional. I was assuming that they would be the Captain's welcome and farewell receptions. The dress code link that Col. Wes posted states "Formal and semi-formal attire is optional on sailings of 16 nights or more", so I'm guessing that since GP is 17 nights that will apply.
As I recall when you book your specialty restaurant reservations on line the events for the night are listed (Captain's welcome, SSS party etc). I wonder if that will be the same?
Jerry will not be alone! Mark will be packing (I will be packing) his tux as it has yet to visit South America. Marc how can you leave your Mickey bow tie at home? It begs to be trotted out with all your finery!