During your Walt Disney World stay, you'll mostly need casual resort clothes. I like to watch accuweather.com for the long range forecast as temperatures in December can really vary. The normal high is in the low to mid 70s and the usual low is in the lower 50s. However, Florida weather can be variable so watch that forecast. You may find that you need more shorts or pants depending on the weather pattern for the week of your trip.
Don't forget to pack a rain jacket as well as a lightweight sweater or sweatshirt to wear during chilly mornings and/or evenings and also in some indoor theaters which can feel cold.
I'm not sure how long your cruise is for but what you'll need will depend on the length of your voyage. See these
guidelines. Also monitor the weather pattern for your ports of call. A lightweight sweater is very handy onboard as some venues can be chilly.
Bring swim suits!
If you are headed to the Bahamas, you should expect day time highs around 78. Of course, weather can be unpredictable so when traveling during the winter months, I like to pack layers. One day can be warm enough for shorts and the next day may require pants. In addition, mornings and evenings can be much cooler than the afternoon hours.
Enjoy!