Plan your days in the Theme Parks based upon the crowd predictions in the Unofficial Guide. Check to ensure that you don't plan to attend any park that has Early Magic Hours in the Morning because during summer months they are significantly more crowded. The unofficial guide has a whole calendar now of which days are most and least crowded. Cross reference it with the latest Extra Magic Hour information on the WDW website or on this website to ensure that you do not ever go to a park in the daytime that is doing Early Extra Magic Hour that day (except maybe for an evening show). Never never never. This is the voice of experience.
Make meal reservations as far in advance as you can for any full service or buffet restaurants that you want to try in WDW. Make multiple reservations at different ones, and blow off the ones that you don't want. There isn't a cost at most of them when you book. 1-407-wdwdine is the number to call.
Learn which two to three attractions are the most popular at each park and do them immediately at open if possible. A good general strategy is to get a fastpass at one, and then do another super popular attraction while you are waiting. After that, the parks can be generally done at your lesiure. The Unoffical Guide has suggested schedules. They work well if you are trying to experience the park in a day, but they will exaust.
Right Now, Sorin (At Epcot) and Expedition Everest (At the AK) are exausting their Fast Pass supplies by as early as 10:00 am for the ENTIRE DAY. Absolutely do those rides first (or get Fast Passes right away) when you visit those parks.
Don't do theme parks more than two days in a row unless you have PLENTY of breaks built in to your schedule. In August, the heat in a Theme Park in Florida can sap your strength more then you can ever imagine. Everyone on their first big trip wants to pack in as much as they can. Less is more at WDW. We accomplish this by ensuring that we take long meals in Air Conditioned restaurants at least once a day. We build a half or full day break into our agendas every couple of days. If you don't see it all (And you wont!)you can go back.
Always arrive 30-45 minutes before open. Plan to stay late to see the evening shows and fireworks. Take a break when it's hottest either by going to your hotel for a swim/nap, or relaxing in a nice restaurant.
Add the hopper option to your tickets. Once you determine what you like, you may want to return to different park in the evening to have dinner or see the show.
Our favorite places to enjoy shows and parades:
Magic Kingdom:
Parades: Liberty square or walking along the boardwalk around the Rivers of America.
Wishes: Take a late break at Cosmic Rays (Tomorrowland) about 45 minutes before the show. Exit the restaurant walk along the sidewalk around the castle toward the front of the park. Great viewing and no crowds.
MGM (Fantasmic). Book a "dinner and Fantasmic" package so that you have access to the reserved area, OR get to the stadium 60 minutes early and plan on eating dinner while waiting in the arena. You book the dinner package at 407-wdwdine just like any other meal reservation.
Epcot (Illuminations). Snare a table in the patio area next to the Rose and Crown 60-90 minutes before the show and trade off while people shop and visit last minute attractions (stay in touch via cell or walkie-talkie), OR make reservations at the Rose and Crown for dinner between 7:00 and 7:15 and request a patio seat when you arrive.
Don't forget to carry stuff for your feet. Antibiotic ointment, mole skin, pre-cut bandage pieces, etc. Wear broken in, but good support walking or gym shoes. Don't attempt to do the parks in sandels or anything "creative". Your feet will pay the price and it will affect your enjoyment of the remainder of your trip.
If it's really hot, purchase or bring one of those little water bottles with fan attached. It will save you.
Agree at the beginning of your trip that if anyone gets cranky or tired, that you will take a break with no guilt attached.
Hava a great trip! I am jealous.
August 18th 
I find myself on it all the time 
