Last summer we did a Grand Gatherings Wishes Pirate cruise with my DD who was 1 and my DS who was 3. We also did an Illuminations cruise when DS was 1. Both times my DS was asleep for the fireworks! My DD was awake last year and enjoyed the music and the colorful fireworks. The Wishes cruise boat was pretty big, but the boat we had for Illuminations was a pontoon boat - it sat about 12. It was fine with DS - he wasn't walking then.
Both cruises were great and we'll probably do another one - a Wishes birthday cruise - in 2007 for DD's 3rd birthday and DS's 5th birthday.
Hope this helps a bit. Please feel free to ask any other questions!