Well, maybe not everything, but most of what you want to see. It all really comes down to one very hard and fast rule...
Have a plan and work the plan!
This seems overly simple, but it really works. It may also seem a bit rough to follow.
We've seen friends and family all easily distracted by a character meet-and-greet on Main Street, a child wanting to "just stop and see the Swiss Family Treehouse -- just real quick," and so on. I know it may sound demanding, but you must stay on task!
When you have a plan, you will see and do much more than you thought possible -- more importantly, you will be able to catch that character you want to see or climb the Treehouse!
Having a plan means putting in some time before you get to the park.
- Look at the times for parades, character meet-and-greets, shows, and other events.
- Remember: FastPass tickets go fast for the most popular rides (did you know there's a limited amount each day for each ride?). Get the FastPass ticket for the most important ride for your family, first. No distractions -- get it, then move on to something else while you wait for your return time.
- Schedule your meals. Don't just eat, willy-nilly. Work your meals into your plan. When are shows? Parades? Etc.? Make sure you're not sitting at Pecos Bill's when you need to be at the parade.
- Is there a parade or show you could miss? This is the time to knock out some rides! So many people are often watching the parade that rides look dormant! You could hit several popular rides while everyone else is watching the parade.
- Work in some rest time! I know, "blasphemer!" you're screaming....but you will ruin your vacation if you try to go full-bore from opening to closing at Disney World. This may mean you'll miss the Hall of Presidents presentation or something, but in the long-run, you will have seen a majority of a Disney World park without destroying your body, resulting in a difficult, sometimes miserable remaining vacation. Remember: It's a vacation! Enjoy it!
Just make sure and follow your plan. 
There's more at Disney World than you can possibly see in one vacation. You're going to miss out on a few things, here and there. With a plan, you get to choose what those "missed" things will be, instead of missing something important.
Remember: The Insider's Guide to Disney has expertly planned itineraries for all age groups (infants, teens, seniors), families of all sizes, and various vacation lengths (1-day, 2-day, and so on). Why not let an expert plan your vacation and maximize your Disney experience? One less "to-do" item on your list and more time for you to enjoy your vacation!
Disney World provides many distractions, but if you have a plan and work your plan, the results will be magical!