Choose a region, how many days you have and your certification. You get a day-by-day plan of sites within your level, easiest first, with the operators documented at each one.
That covers every documented site within your level in Cairns in 1 day. Use the spare days to repeat a favourite, or add a neighbouring region.
Plan with a safety margin. Keep the deepest dive first in the day, allow a surface interval of at least an hour, and leave 18–24 hours between your last dive and flying. Book with operators early — offshore trips are weather-dependent.