Dress in what you want! If you want to get into that full length evening dress, then go for it. You won't be the only one. Get dressed up as you want to. Its a great excuse to get some good portraits in formal wear.
Understand though that not everyone is going to be dressed to the nines. Especially on the Texas departures, the "formal dress" code for Galveston includes dress cowboy wear - Hat, buckle, fancy boot and dress jeans... Because that IS formal wear in a good portion of this state.
But we dress up because of the fun..
Carnival Cruise Lines:
Fantasy 90, Celebration 95, Victory 05, Conquest 05, Spirit 6/06, Freedom 6/08, Holiday 7/08, Victory 6/09, Valor 9/09, Dream 6/10, Splendor 8/10,Conquest 8/11,Magic 11/11,Triumph 4/12,Spirit 7/12,Freedom 11/12, Triumph 2/13 - The fire cruise
NCL Dream October 2006, RCCL Mariner OTS June 2007, Celebrity Silhouette 2013