Hi--we did the 3 night last October as well! It was so fun--you're going to have a great time!
Tritons night: semi formal
I wore a short black dress, my DD5 wore a dress, husband wore a suit and tie(if you don't like that, you could just wear a jacket), and DS9 wore khakis and a blazer.
AP: resort casual
I wore a sleeveless linen dress, DD5 wore a dress (she always wears a dress, lol), DH wore khakis and a button down shirt, DS9 khakis and a button down.
PC: resort casual
I wore capris and a sleeveless sweater, DD5 wore a dress (lol), DH wore khakis and a golf shirt, DS wore khakis and a golf shirt.
It was very warm at that time of year; we wore shorts every day and it was easy to swim (the water was a bit chilly). You might bring a light sweater, esp. for dinner or the theater, but even at night we could be in shorts on the deck.
I would urge you to bring a carry-on type piece of luggage that is empty that you can put stuff you buy in when you leave; we had a hard time fitting that in to our bags!
I also think next time I will bring a suitcase that has an outfit (including shoes) for everyone for the morning that we disembark. That last night, your bags have to be out in the hall by 11:00, and it's too hard to try to go through and pack everything, and you miss your last night on the cruise!!!! I will just leave out PJs and have one suitcase for the morning, and toss everything else in the bags for them to take and worry about it when I get home!
Last idea--the over the door shoe holder really is a life-saver for toiletries. There's not that much room in the bathroom, and you can have everything out and be able to get to it.
You didn't need THAT much info, huh??? LOL, sorry! HTH!
Amy