Personally, I prefer short. Easier to pack. Plus, when young, I had to wear long gowns, so now I don't want to. I also often go for dressy slacks and top for cruises. But, anything dressy...it's all good.
Shorter for me, easier to pack and takes less room in the luggage. They tend to say, the second formal evening is more formal than the first, usually there is a cocktail party, but the dress really doesn't matter as long as its formal and you are comfortable in it.
Punk, like you that is my personal preference, long the first formal night and then a short cocktail dress the second formal night.
I have found some gorgeous, classy dresses thru the Barrie Pace catalog, a bit pricey but try to hit the sales, have also had some really good luck thru the Chadwicks catalog, both have web sites you can check out.
I personally like both styles. The most elegant, IMHO I'm actually packing for this trip is a very simple ivory cocktail dress which caught my attention because it's very well cut and certainly the most expensive I have but I think I may actually wear this for the supper club instead since it is a little on the simple side.
I do try very hard to stay away from black, which I love, but I have worn so many black dresses in my life! However, I always end up with a black number as well whether short or long. My most plush in terms of looks is a bubble hem halter neck royal blue silk one (short) but I'm not sure if I'm packing that or not. It's a little bit on the extroverted side, not tarty just not something you would wear if you want to melt into the crowd. This maybe good for other evening activities like dancing or going to the casino though, so maybe it'll pack it anyway. I'm packing a teak colour long halter neck also which I will probably wear on one of the formal nights. I'd love to be more creative with colours sometimes but I have natural red hair so a lot of stuff just doesn't look too great on me.
After years of shlepping two piece cocktail dresses, I finally broke down and bring a pair of palazzo pants.. black..and have several dressy tops I can wear.. Picked up on sale at the end of the season .. a gold knit sweater..which I think I''ll wear with white dressy pants.. Yes, I would love to bring lots of cocktail outfits, but we have to fly to o ur cruise ships.. For heavens sakes I've seen ball gowns on cruises... I too hate the black bit, but since I was never a black person....although have velvet long skirt.. but that doesn't seem to go on cruise ships..You can look simply elegant too with just a simple long or 3/4 length dress and the right jewelry and bag..