We haven't done an illuminations cruise but we have done the wishes cruise. We were lucky enough to be with a group on Grand 1, it was magical in it's own way The music is piped onto the boat and it harbours up facing the MK so you can see the fireworks. It feels like you are the only people out there until you look both sides. The good thing with Grand 1 is that none of the other boats are allowed to be in front of you but it is very expensive to book Grand 1.
One thing to be careful with is that not all the firework cruises have the music piped on board, so be careful when booking. I think it's the basic pontoon boat that doesn't but I'm not completely sure.
You can book this from 180 days out on on 407-939-7529
One other thing to add to your costs is that it is customary to give the captain a gratuity.
You also get to see the Electrical Water Pageant up close