I would suggest the following tour. This assumes that you would like to experience everything and you like thrill rides.
First and foremost, arrive before the official opening time. Epcot security is the slowest of all the parks. Have your bags checked and inside the Epcot gates at least ten minutes prior to official opening. When the park opens, immediately walk to the right of Spaceship Earth a/k/a The Big Silver Ball. You will follow the path to the right until you reach Innoventions West. Turn right through the passageway. Straight ahead is The Land. Enter into the building and immediately go to your left and down the stairs. Turn to your right and enter the Soarin' line. After you ride Soarin' immediately to the Living With The Land ride.
When you leave The Land building, turn to your right and head to The Imagination Institute. See Honey I Shrunk The Audience. After seeing this presentation, you will want to send someone over to Mission Space or Test Track to grab Fastpasses. While they are gone, some of you can see Journey Into Your Imagination with Figment. By the time you have ridden the ride, your party should have returned with the Fastpasses. Your Fastpass will have the printed time you are to return to the ride and it should have a printed time on when you can obtain your next Fastpass.
If you Fastpasses are not for over one hour, head over to either the Living Seas (which is straight ahead from the Journey to Imagination) or head back to the passageway near Innoventions. Your time in the Living Seas depends on how long you linger over the exhibits and whether or not you stand in line to see Turtle Talk With Crush. Since you have adults and teenagers, I would suggest skipping Turtle Talk.
If you head back towards the passageway, you need to go straight through the passageway and head toward the passageway straight in front of you. Spaceship Earth will be on your left. After passing through passageway number two, you will go straight and turn left towards Universe of Energy. This ride takes a little while (over 30 minutes) so keep this time in mind for Fastpass purposes. See if you can now obtain more Fastpasses. If you can, go ahead and obtain Fastpasses for Test Track or Mission Space. Because both of these rides are extremely popular, all Fastpasses may have already been passed out for the day. Be sure to keep this in mind when you are deciding on which of the two to obtain first.
You are now well into the day and if you have time before your Fastpasses, stop for a bite to eat at a counter service location. Some people do not like to eat prior to riding Mission Space but it has never bothered anyone in our group.
Your Fastpass return time should be coming up soon. When you leave either Mission Space or Test Track, head to Spaceship Earth (a/k/a The Big Silver Ball). After riding Spaceship Earth, you have now experienced all of the major Future World attractions.
If you are not interested in touring World Showcase, you can now visit all the minor Future World attractions. Both of the Innoventions buildings (located directly behind Spaceship Earth) house many, many interesting exhibits. We seem to like the Innoventions East building best. You can build a plastic robot (free to take home-making this a cheap souvenier) and then you can build your own virtual reality robot which you will race against eleven others.
You can also go back and explore The Land some more. You might want to consider taking the Behind The Seeds Tour. It costs about $12.00 for adults and we really like it. You get a behind the scenes tour taking you through some of Epcot's experimental gardens. You also get to see some of the sights you saw on the Living with the Land ride.
OOOHHHH I almost forgot. When you leave Spaceship Earth, head back towards the large fountain between the two Innoventions buildings. Straight ahead you will see Club Cool. Inside Club Cool, you can sample Coca Cola from several different countries and it's free! Be sure to sample the watermelon flavor and the citrus.
Hope this helps you guys out. If you need World Showcase tips, let me know, Lisa