I am subbing in on this thread too as we are also interested! I was speaking to some extended friends on the weekend who recently came back from a 5 day cruise with their 4 and 6 year old. They loved it. The cruise they went on was out of Singapore on a boat called, I think, "Legends of the Sea" or something similar - it was an american cruise company.

Apparently where the cruise went was places like Phuket for a day and the water was really calm through the Straits of Malacca (sp?). They would recommend it again. They also had 2 cabins with interconnecting doors.