we do this all the time. for ladies, here's what I do: travel size bottles of whatever, no hairdryer (use the ships), wear biggest shoes/boots, then take 1 pair of black flats, 1 pair flipflops, 1 pair sneakers, 1 dark skirt or thin dress with 2 scarves, 1 extra pair of dark pants/capris, 2 sweater sets, plus wear one, lightweight waterproof (or repellent) jacket (windbreak-wear on plane), medications, minimal makeup, swimsuit, underW. Rewear dark bottoms. In spring, you'll not get very sweaty, so can rewear sweater sets. you can throw in a few extra tank tops, to switch around. Above fits into carry on. For DD (teen) shirts, tanks, 1 hoodie, jacket/raincoat (wear), jeans, 1 skirt, leggings, yoga pants.
DS- wear jeans on plane, take 1 extra jeans, 1 khakis, 1 shorts, 1 colored dress shirt, 2 polos, rest tee shirts. I pair low rise hikers (which can double as dressier shoes) and tennis shoes. Same for DH, except he doesn't take jeans and takes mostly polos.
Key is to limit everyone's shoes (I wore flats and not heels to dinner), take darker bottoms which can be reworn, and for you, wear a dark skirt/black dress mulitple nights with different scarves, etc. to make a new look.
If you have a cruise that has washers, use them for 2 loads midweek and cut down even more. I would much rather throw a load in the wash and be able to cut my luggage by 1/3 or more.