We were there in January with our 2 year old. First of all, we were surprised by how much she enjoyed herself. She loved the rides, the characters, the food.
Things she really liked were the teacups, the carosel, the Barnstormer roller coaster, Aladin's carpets, Tricerotops Twirl, Kilimanjaro Safari, Festival of the Lion King (although at the end it got a bit loud and she didn't like that), meeting Mickey, Minnie, Stitch and Goofy, the chicken noodle soup at the Indian chicken stand in AK and being made much of by the CMs in the China pavillion (DD was adopted from China).
Things she was ok with were Pooh, Snow White, Peter Pan, Haunted Mansion, Pirates, Maelstrom, Rio del Tiempo, the two animal walks at AK (although the bats were a prime favorite which she still asks after) and shopping at DTD.
Things we have no clue about because she slept through them are Tiki Birds (the Gods alone know how), Spaceship Earth and Jungle Cruise.
We did not get to MGM so I can't talk about it. MGM is my DH's least favorite park and I could not get him to go - however DD and I are going back for a "mommy and me" two day trip in May and I ho pe to get her to MGM for the Muppets and Little Mermaid shows.
What she did need was down time, just playing in the hotel room for example, something resembling her regular nap schedule and access to her favorite comfort food, rice.
Good luck and have a wonderful time. Be sure to have your camera with you and don't rely on the Disney picture takers at the character meetings. They never got as good photos of our DD as we did. Oh and one last thing - adult beverages are a good thing.
