I have had to Magic Kingdom cruises that were iffy right up until departure due to lightning. so far we have had luck!!!! The Epcot boats are always not available. I read there are only 4. Compared to MK's 12.
I have done the party package on the MK boat.. It was a huge chocolate Birthday cake, (That everyone said was the best cake they ever had,) Paper goods, and a cooler full of soda and water. Candles were not allowed for the cake, No fire? So we used little light sticks, I just happened to have. I will go to Seashore sweets and get some treats and bring them with us!
For specialty Cruise information/ Booking.... It is 407-wdw-play 90 days prior at exactly 7am!!!!!