Hello Romana,
I'm so jealous! What a wonderful trip you have planned...Disney World and a Disney Cruise? Your kids should be kissing your feet!
As I'm sure you know, that time of year is extremely hot. Obviously, shorts, and tshirts are going to be your outfits of choice at the parks. Don't forget the bathing suits...Disney resorts have awesome pools! For dinners, it really depends on whether or not you have any fine dining reservations. You would want to adhere to their dress code, but normally it is more of a "business casual" look, you know, pants and a polo for men, capris and a blouse for women.
Typically, your Disney resort will have laundry facilities which means you can actually launder your clothing right before you go on your cruise and you don't have to pack for two trips. There are also laundry facilities onboard every Disney ship. Here is the
dress code for Disney Cruise Line. I've also included a suggested
packing list that will also help.
I hope this helps. Please let me know if I can answer any other questions for you. Thanks for visiting the Moms Panel. Bon voyage!