I went on one last October and am going on one in February (the coldest time of the year here!). Make sure you start with your neutrals. For example, I'll be taking 2 pairs of ankle pants in navy and white; two pairs of capris in sapphire and navy; two pairs of shorts in navy and white. Then I add white t-shirt, navy tank top, short sleeved sapphire t-shirt, and maybe a wrap shirt in navy or white, and a short sleeved white button shirt. Formal wear I haven't made up my mind yet. I have very bad feet, so I'm limited largely to tennis shoes and tennis shoe-like sandals. Anything I wear has to hide the shoes, so likely cocktail pants. I don't wear dresses or skirts because of the shoes, but you could certainly get something in a neutral. A black cocktail dress might work for the formal nights. Finally, make sure you have something that will work for the actual flights, since you will be changing weather zones. You don't want to show up in a snowstorm wearing a tank top. Jeans and a long-sleeved shirt would probably work there.