I am always accused of overpacking, but for me it is worse to get there and feel like I don't have what I need. Warm climates like Florida are easier.
1) make a packing list; reuse it for every trip and you will learn to get more efficient each time
2) pack 1 outfit or less per day for the expected warm weather (i.e. tanks/shorts). Some of these are probably quick-dry shorts and shirts, so rather than doing laundry just wash them in the sink at night and hang them to dry... you'll get an extra outfit without taking vacation time for laundry.
3) For cooler weather, take 1 or 2 lightweight jackets or shirts that can be worn more than once.
4) I love the convertible pants from REI. My last Disney trip was in February. All of us wore these pants often in the morning, and zipped off the bottoms to put in our backpack during the day. These are also quick-dry, so easy to wash and are great for water rides. Any wrinkles they get in your suitcase come out instantly. They have velcro pockets and zip pockets so you can even carry your cash and credit cards right in the shorts.
5) Shoes are bulky. Take 1 good pair walking shoes, 1 pair sandals. If you really must take dressier shoes, find 1 versatile pair. If space is an issue, also remember to use the space in your shoes to pack socks or whatever else fits in there.
6) Get a personal organizer bag from LL BEan. This will hold all your sample-size shampoo, detergent, etc (even hair dryer if you get the large one). When you get home from your trip, just refill the bottles and it's ready for the next vacation or trip to the gym. It also comes with a little hanging insert that you carry to the shower on each trip so your stuff isn't scattered around the hotel room.
7) Like to take books? Maybe 1 paperback if you must; otherwise carry an MP3 with books on tape. You can hold a lot of books in the palm of your hand!
8) Take a backpack instead of your purse. This will allow you to leave home the grocery store cards, extra credit card, etc. that usually bulk up your purse. Then the same bag you carry on the plane can double as the bag you carry around Disney all day and will hold the camera, rainjacket, etc safely with you.
Or just decide you are an overpacker, buy huge suitcases with wheels, and have a blast
