Hi Michael!
I remember when our family was planing our first ever Walt Disney World vacation and we had the exact same question, "What are the must sees?"
The absolute must sees are the things that you and most importantly, your little ones, are most connected to. The princesses, Star Wars, Liberty Square, dance shows? The list can be very lengthy or very simple.
Once you have decided what the most important personal attractions are then go to the
Walt Disney World web site to learn about all the attractions that are available. You may learn about something that you didn't even know existed at the parks.
My personal "must sees" every time are the parades and any of the fireworks shows.
Have a very magical time!
Carrie