You will be allowed to stay in a standard room at AKL, since your youngest will be under 3. You will only have bedding for 4, however, either two queens or one queen, and a set of bunks. Your youngest will be expected to sleep in a crib - unless you can work out some bed sharing. I know my 3 year old loved sharing a queen bed with Mom & Dad - she still migrates in between us fairly often, and she is almost 7 now!
They also have deluxe rooms at AKL - a little larger footprint - with a queen, 2 bunks and a daybed - about the size of a regular twin bed. We stayed in one of these last December - awesome!!