Hi Carrie,
It's always great to hear from a fellow Bay Stater! I absolutely think you should visit Epcot with your children! If you have a Park Hopper, you may want to plan on a half-day there and a half-day at Hollywood Studios (you can take the ferry boat there when you exit through the International Gateway at the back of Epcot).
When my youngest two were 3 & 5, they loved the
Seas with Nemo and Friends Pavilion. In fact, at 6 & 8, they still want to spend hours in there. It begins with a slow moving, mesmerizing ride that ends in a multi-level aquarium. Your children can enjoy seeing dolphins, sharks, sea turtles, manatees and countless different kinds of fish.
Another fun attraction for them will be the
Imagination Pavilion. This is another slow moving ride which ends in an interactive area. At 3 & 5, my little ones loved the "musical squares" that they can jump on. It's essentially a rug and when they jump on the magic squares they make the sounds of the picture they see. Like drums, an elephant and more. They can also "conduct an orchestra" with their hands. This area is a lot of fun for kids.
Depending on how tall your 5 year old is, you may want to take them on
Soarin' (must be 40 inches to ride). My kids all love this attraction.
You can also visit the
Kidcot Fun Stops in the World Showcase. These colorful craft stations for preschoolers make "traveling the world" a lot of fun.
Wishing you a wonderful vacation,
Kaylene