Planning will be key here. Also, take advantage of Fast Pass and get to the parks early each day. If you can, download current park maps and schedules for the weekend and study them. Too many people waste time initially going over the map and then figuring out where things are and what to do then and there.
Make PS's for at least some key meals in advance also. That will save you time too. Get snacks &/or light meals on the run.
The parks:
Epcot - Since it is the largest one, plan to be there the whole day. You can take breaks within the park, so there is no need to leave and then come back. Skip Spaceship Earth initially. Tons of people line up there first thing, while later in the day there is often NO line. Grab a Fast Pass for Test Track or Mission Space instead and then explore around Future World. Go to Honey I Shrunk the Audience or the Living Seas before TT or MS. When World Showcase opens I often head towards France or Italy first and then wind my way back towards Future World. Again, crowds hit Mexico and Canada first. If you can and like, plan a dinner at the Rose & Crown to start around 7:30-8pm to sit down after a long day and watch Illuminations from there. Make a PS though.
MK - This park often stays open late on a Holiday weekend. Don't linger on Main Street initially. See it later. If the street is crowded, remember that the gift shops connect and you can often breeze right through there with fewer crowds (except at the end of the day). Head towards the far reaches of the park, such as Splash Mountain and get a Fast Pass. Then hit the other highlights and work your way back towards Main Street. If you are willing to skip the afternoon parade, go to Toon Town or Fantasyland then (late night is good too).
MGM - Make sure to take in a stage show or two. These are great and not to be overlooked. Pick a Fast Pass of your choice and skip over The Great Movie Ride until later in the day. Lunch times can be good for Indie Jones (bring a snack with you) or the Backlot Tour. If you can get a Fantasmic dinner package, do it. It will assure you a seat at the show.
Do any shopping early in the day or by mid-afternoon. Have the packages sent to your Disney Resort or put the packages in a locker for later pick-up. The shops are a zoo before park closing. Use that time to get in any last rides or attractions.
