Be sure to start a packing list now. When it gets finalized, make a copy. Use the first copy to pack with, marking off each item as you go. Put the other copy in an accordian type file in your carry on and use it to pack when you return so you know you haven't forgotten something. I make copies of all my paperwork (resort conf #, ADR#, itinerary, airline ticket e-mail receipts, DME stuff, packing list, etc), place them in two accordian type files, and place one in my checked luggage and the other in the carry on. Dont forget to add your last minute stuff (contact lens case, makeup bag, etc).
Pack as light as possible as most people have a tendency to overpack. In their travel section Target has a small bottle of liquid Tide, with a measuring cup on it that does four loads for .99. I put one of those, along with some dryer sheets, and a roll of quarters into a gallon zip lock bag. I have also bought one of those cheap laundry bags at
WalMart's which I hang in the closet and put our dirty clothes in as we take them off. I hate to come home to dirty laundry and since I'm a very early riser, I do laundry a day or two before I come home. It doesn't take long and I love getting up early and walking around the resort while I'm waiting for my clothes to get done.
As far as packing, again pack as light as possible. I love jewelry, but when I travel I usually pick one set of plain sterling silver that will match everything and then just wear it for the whole trip. Also buy travel size toiletries whenever possible. I always make a trip to Bath & Body works just for their little travel size bubble baths, shower gels, lotions, and sprays they sell at the front of the store. Buy a scent you don't normally buy and when you use it after the trip, it will remind you of your WDW trip. Pack your stuff in zip lock bags, squeeze the air out and more will fit in your suitcases. It also makes it easy to get ready in the morning if all you have to do is pull one bag out and you know everything is in there (underwear, shorts, shirt, hair scrunchy, etc). Also be sure to pack anything that might leak in zip lock bags, i.e. sunscreens, sun burn relief gel, toothpaste, bug spray, bath products, etc. Wear your bulkiest pair of shoes and a jacket if you plan to carry one in order to save room in the suitcase, but I would carry at least one extra pair of shoes in case the pair you're wearing gets wet. Personally I like Teva sandals and flip flops as they are lightweight, take up very little space, and dry quickly. Also be sure to carry any extras you might need, like an extra pair of contacts

. Just be careful to weigh your bags before you leave, as it is VERY easy to get over the 50lb weight limit.
One more thing, if your 6 y/o has a certain toy she must have, be sure to warn her it will have to go through the exray machine. I took my GD to San Antonio last summer and as I put her carry on bag on the belt, she screamed, 'Bunny's in there' and almost climbed onto the belt with her bag. Once we got both her and her bag through, she insisted on checking to make sure her bunny was OK. When I took her to WDW in January she was expecting it, so was fine. That machine can be pretty scary for a little kid. Also warn your kids that they will have to go through security and make sure they have as little metal on as possible. Same thing for you and your husband, (no belts, no light up shoes, no metal on shoes, no underwire bras, be sure to empty all change out of pockets, etc). You don't want to get hung upwith security.
Make your lists so you don't forget anything at the last minute and have a great trip.