Ok, I have some advice that goes "against the grain".
First, nix the idea of a complete outfit per ziploc bag. It just doesn't work. What if you have to change one item of clothing during the day--say a soiled tee-shirt? Then you find yourself digging through all the other outfits, then they're not complete, so you dig through other bags again, etc. Instead, here's what works for me--
Pack all like items per ziploc bag and label. For example, ds socks. DD' underpants, etc. Also, pack another, same-size ziploc inside that bag labeled ds dirty socks, etc. We used to stuff dirty clothes in the laundry bag provided by most hotels, then found out when we went to pack that we had one huge dirty clothes bag that simply wouldn't stuff back into the suitcase. This way, as one bag gets smaller, the other gets bigger, so at the end of the trip you have the same "bulk" as you started. Plus, yoiu know at a glance where to look for socks, shirts, etc. I like to take a few minutes the night before and set out my kids (and mine) clothes for the next day, but you can't always predict the weather, circumstances, etc. so you don't know what would be an appropriate outfit until that day.
Also, I always wince when I read "don't overpack". Yes, you don't want to be burdened down with everything you own, but don't short yourself, either. Always pack one more of everything, such as one more shirt, underwear, pants, etc. It doesn't take up that much room and you never know what might happen. Clothes get torn, stained, etc. And do plan for just about any type of weather. I've seen more vacations ruined by not having "contigency" items. Last trip to WDW, one night, the night of
MVMCP, it was hot and muggy and I wore shorts and a sleeveless blouse. The very next night, for the Candlelight Processional at Epcot, it was cold enough for jackets, sweatshirts, hats and gloves (which we had!). However, that same afternoon, we went swimming at our hotel pool (packed bathing suits). How you pack kind of depends on how you travel. If you're on the road every day, a different hotel every night, well, you really want to keep the luggage to a bare minimum. However, if you're staying in one place several days, you're not lugging stuff every day and can take a little more.
Also, I always pack my "pharmacy". It goes without saying you pack your prescription drugs, however, pack anything over-the-counter you think you might need, such as Tylenol, Inmodium, etc., along with first aid stuff such as band aids, antiobiotic cream, etc. Yes, I know, there's always
WalMart wherever you go, but do you really want to spend precious vacation time hunting down a WalMart for something you could have easily packed?
The trick is to take a little of everything--clothes for just about all temperatures, clothes that "mix and match", contigency items, etc.
Also, instead of lugging baby stuff such as diapers, wipes, etc. formula, bottled water, etc. have you considered having them delivered to your room when you get there? Its really not so expensive as you might think. Last trip we used a delivery service
www.wegoshop.com. You just fax or email them your list, you can even specify what store, call them when you get to your hotel, and they deliver right away. I think in our case we waited 20 minutes. The delivery fee at the time (might have gone up) was $10 for orders up to $100, then more over that. We ordered bottled water, milk, fruit, breakfast bars, sandwich fixings (we had a fridge in the room), along with soap, shampoo, etc. Beats lugging it!