Hi Michelle028...Congrats on your upcoming cruise on the Liberty..
If you are on a 7 day cruise you will have two formal evenings. Cruisers dress in various attire for the evening from tux/cocktail dress to suits and/or sport jackets and tie to less informal..If there is a meet the Captain, you will have a chance to meet the Captain and some of the Officers and have a cocktail. There are so many opportunities to have your picture taken that you can purchase. There isn't much difference from the other dinners in the main dining room except a little more extravagant.
Enjoy your cruise !