Really, the whole issue of getting a good seat is not important with a little one. You are much better off getting there later and sitting near an aisle in the back. There are 3 reasons for this: 1) it is not as loud in the back, 2) the figures don't seem to loom over you as much, and 3) you can get out from there with a lot less walking, which is important because you must leave strollers in a holding area completely outside the theatre, and you'll have to carry your child in the exodus crowd.
The other thing I would advise is to make sure that your child has seen "Sorcerer's Apprentice" & "Sleeping Beauty" beforehand. (Either Fantasia movie will do; "SA" is in both of them, but the original also has the dinos that are in Universe of Energy at Epcot.) My DS is not afraid of Maleficent, but he's terrified of the sorcerer, so go figure!