In my experience, and I'm sure it'll be echo'd by others on the board, any time school is out is going to be a crowded time. If it were me, I would definitly get the package for the april trip.
I was looking into the package for our january trip, and I decided against it, exactly for the thoughts listed above. From what I'm told, the seats aren't the best. I'm willing to wait a little while to get better seats.
Also, orlosipher-
Last time I was there was in 2004, and I opted out of seeing it because I was afraid it would scare my then DS2. My sister went with her DD2 and she was terrified...... Apparently there are some scary parts.
Just want to make you aware!