Hi Cynthia! I think you could easily enjoy a day in EPCOT with your three year old daughter. There are a lot of attractions that she can enjoy.
I would recommend an advanced dining reservation at one of the World Showcase restaurants so you can rest and relax for your meal. You can check out the menus for these locations by going to
www.allears.net and then typing in MENUS in the search box. You might want to consider a character meal such as dinner at Garden Grill or one of the princess meals at Akershus in the Norway pavilion. To make the reservation please call 407-939-3463.
EPCOT is a great park to walk around even if you are not doing all of the rides and attractions. It is so beautiful with the greenery and floral everywhere. Make sure you have a stroller with you for your daughter. If you don't bring your own you can rent one for the day for $15.00 at the entrance to the park. Take something to put on the stroller to help you designate it easily when you are parking it among the many! We often used balloons or scarves.
The following are great attractions you might enjoy with your daughter:
The Seas With Nemo and Friends
**Turtle Talk With Crush**-a must and favorite of mine!
Living With the Land-boat ride
Journey Into Imagination wtih Figment
Imageworks-interactive area following the ride
Possibly Spaceship Earth and Universe of Energy??-depends on each child interest level
Kidcot arts and crafts areas at each country and several Futureworld locations
Gran Fiesta Tour boat ride in Mexico pavilion
If you need any help with supplies or just need a rest head to the Baby Care Center located in Future World by the Odyssey Pavilion.