We have made several trips to WDW with our 5 kids, ages currently 16, 7, 7, 4, & 1. In fact, I have taken the 5 kids myself without dh a couple of times, and will do so again this summer. Difficult, but doable. That said, I guess my #1 tip would be this: take your dh! *Much* easier w/ 2 adults, lol!
Other than that, plan ahead and include the kids in the planning. Agree AHEAD OF TIME, so there's no fighting about plans *during* the trip. Take note of certain rides, restaurants, whatever, that each child considers a "must", and then try to include these in your itinerary. (You do have an itinerary, right??

) Make sure everybody understands and agrees that it's "no fair" grumbling about going on less-favorite rides that others really like. Everyone will get to do their favorites.
Split up at times. One of you take the older kids to the rides/attractions they like, the other parent takes the younger kids to their favorites. There's no law saying the entire family must remain joined at the hips for the entire trip! Plan to meet up a couple of hours later. Pick a spot to meet that is close to a restroom and also a snack or ice cream cart in case one party has to wait for any length of time (like if one party is stuck in line for a ride longer than they thought they'd be).
Take freqent head counts when you're walking thru the parks. Kids stop to look at something and the rest of the group keeps going, not noticing that one person is missing because there are so many people in the group. One trip, our mantra was "Where's William??!!" And hold hands--use the buddy system for anyone not in a stroller.
Try to pack as lightly as possible. Lots of people = lots of (heavy) luggage. Luckily, you're going in July so all you'll need is shorts & t-shirts. Plus you'll have a handy-dandy washer/dryer in your OLCC villa. Toss in a load every night or 2, and you won't need to pack much.
At restaurants, unless your youngest 2 are really big eaters, have them split a kid's meal--there's usually plenty of food for two kids. Make sure the older kids know ahead of time if there's a price limit on what they can order. My dd16 would have ordered the most expensive steak on the menu every time if she had her way!
That's all I can think of right off the top of my head; feel free to PM me if you have any questions.
Sue