We are planning on taking just my 2 year old when we go this time ( I have been there with my older children before and they are now 14 and 17). Our plan at this point is mainly to just go to Magic Kingdom and Animal Kingdom. I don't think Epcoit will hold any thrills for her, as my older two mostly liked the video game areas and test track. Both of which she is too young for. The other stuff was OK there, but it wasn't the kids favorite and we always ended up gong back to the MK. MGM, isn't a favorite of mine either. We have only spent to half days there and got bored, so I don't think we will hit that again until she is older too. The one thing is I'm not sure I want to pay the extra for a park hopper so we can see the fireworks or parades if we want. But we haven't booked yet ,so i will decide then. Depending on what a deal we get.
We have always done the MK first, and the kids want to go back alot, but did enjoy going to different parks as well though. It was just their favorite. So I guess you need to decide too if you want to hit all the parks, or not and if you want ot be flexible when you get there or plan right away which parks you are going to and stick to it.
Also some of the simplest dumbest things are big hits with the kids. My kdis liked running through the water sprinklers. I think a few of hte parks have them, can't remember which. At the Animal kingdom we could've spent all day in the dinosuar dig area. Things that aren't really even advertised as big attractions were just amazing to them. Fireworks were fun and the night parade was a big thrill too.