I haven't read the other responses, so sorry if any of this is a repeat. I took my dd at 2.5 last year. My best advice is to prepare the 2.5 year-olds for the dark rides. My dd was never afraid of the dark, but was wary of the dark rides at first. She hated pooh at first, but by the end, she loved it. This time (feb. 8-13) , we will show her videos of the rides on youtube and be sure to explain that they make it darker in there so you can see all of the pretty colors better. I also told her when she was afraid that she could sit on my lap and if she was afraid, I would hug her and she could hide her eyes. She only had to do that with the scary fish on the Nemo ride at Epcot.
Her faves were Pooh, Mickey's Philharmagic, Small World... this is a good first dark ride not quite as dark as some and very happy and mild. I think we did pooh first and there is a part where your honey pot bounces along with tigger. She didn't like that part until we explained that she was bouncing with tigger and then found it didn't move her around as much in her seat if she sat on my lap. By the last day, she wanted to ride Pooh 3 or 4 times that day. Dd is a big pooh fan, so we make sure to go to crystal palace for dinner. Wishes is a MUST for us, and multiple times and we must be in front of the castle for it and in a place where we can see Tinkerbelle fly from the castle (off to the right).
At AK, she loved the Nemo show and Pocohontas. If your kids are playhouse disney fans, then Studios has a show that is supposed to be revamped and I think it will be open at the time you'll be there. I heard they are adding mickey and some of the more recent characters. The lunch with jojo and little einsteins was good and had a lot of kid-friendly veggies when we were there. Our dd got sick of carrots last trip, but they had corn there and some others. She loved jojo.
We are not huge fans of Epcot, but like the Nemo ride (if eyes are covered during the scary angler fish part) and Turtle Talk with Crush. We can miss Illuminations, but love LeCellier for lunch or preferably dinner. This was a last minute trip, so they only had lunch ADR's for LeCellier this time.
2.5 was a great time to go, but don't feel discouraged if they are afraid of anything. I found that explaining why they do something and pointing out how silly things are really helped my dd. I will make sure to remind her this time befor ewe go. She remembers a lot about last year's trip, and it was in Nov, so a full year ago. She still tells me things that she remembers... very random things sometimes! LOL!