"I'm trying to figure out how to pack. Will it be warm enough for swims suits and shorts? What are the night time activites? What should I plan to wear for those? I'm having a hard time figuring this out! But I'm so excited!"
I've taken this same cruise around this same time before. It was cold on the day of arrival, so I dressed warm. I also wanted to be comfortable, so instead of jeans, I chose to wear some athletic-type pants & a hoodie. Even if it isn't cold on embarkation day, you should definetly pack something warm, just in case it is cold upon the return to New Orleans. (very likely in January) Regardless of what the January weather is like in the states, the temperature should get warmer the closer you get to Cozumel.
The night life on board the Elation is like most other ships. It can be whatever you desire, from relaxing in a hot tub to vegas-style shows, comedy acts, to partying at several different clubs & bars. I recommend packing for each possibility cuz you never know what you will be in the mood for.