The "tropical" rhododendrons
Most of the Rhododendrons you'll see in northern hemisphere garden books are shrubs of cool climates. They aren't suitable for gardens in most of Queensland (unless you count the Azaleas). The Vireya group of Rhododendrons come from warm regions of the world, although usually the cooler mountain habitats. Australia even has a native Vireya, R. lochiae (Some authorities believe the Australian Vireyas should be divided between two species).
Plant breeders have a done a lot of work to expand the range of cultivars available. A notable feature is their amenability to container culture (many grow as epiphytes in nature).
More Online Information
The following are for general information, research and ideas - some species or cultivars referred to in links may be unavailable in Australia or unsuitable for Queensland conditions
notes about these plants in Hawaii. Pana`ewa Rainforest Zoo, Hawaii