Hi, Melissa ...
First of all, don't worry about your weight. I have a friend who is quite heavy and her attitude is, "If you don't like it, don't look at it."
She has recently been wearing some clothes that I think would be absolutely perfect for cruising. The name of the line is "Flax". It's supposed to look wrinkled (!) and she said she packed for a 10-day vacation with one dress, two pair of capris, two tops, and a jumper. It rolls up, she says, for easy packing. She also has another dress that is extremely lightweight which works as nightshirt, beach coverup, whatever.
The outfits are mix and match and I think they are quite flattering for what my pal calls the "generous" figure. The fabrics are really cool.
She's bought most of her stuff on e-bay but she says to try angelheart.com as well.
What I would take for the formal nights would be a silk pants and tunic outfit with some hot costume jewelry. The "Flax" would do for both casual and informal nights, especially if you were to wear the dress with a nice scarf or interesting jewelry.
Don't forget your bathing suit!
You will have a great time.
pamda -- CM First-Time Cruisers Editor