Hi RE Guru. Just had a look at the other cruises you are doing. Great Barrier Reef is a good cruise. Lots to see & experience our tropical north. On our cruise you will have opportunities to snorkel at Mystery Island & Lifou. Not sure how long you have in Brisbane but I would suggest visiting the Gold Coast (about 90 mins drive south from Brisbane City). Australia Zoo (Steve Irwin) again about 90 mins drive north from Brisbane City. In Brisbane itself, South Bank & Lone Pine Koala Sanctuary.
Steve.