I personally think the cladding would look nice and be the easiest to maintain. We also live on the Gold Coast and have a brick house that has been rendered (not by us) and, to be honest, it is not particularly low maintenance (if you want it to stay looking good that is). It is prone to leaching which leaves ugly stains so regularly needs retouching with the paintbrush. It can also develop small cracks in the render due to temperature change and movement. However, the most worrying thing for us is with regards to termites. If you render over your brick on the lower half of your house, it is highly unlikely you will see the telltale "mud" they leave that indicates they are trying to gain access into your house (they climb up in between the render and the brickwork). I would be trying to keep the exposed bricks in preference to rendering over them, particularly if you have a garden bed up against the house anywhere.

For a cheaper, faster and possibly easier option, take a look at this for some inspiration. The lighter colour of the walls may reflect more light and be a stand out feature of your home. Click on the link and scroll to the image of the polished timber floor with the timber wall and ceiling. Polished timber floors with timber wall paneling

Yes, our harsh Australian environment does hammer our external finishes but if exposed timber is coated with a good quality finish initially ( i recommend 4 coats minimum ) then an ongoing maintenance coat every couple of years, your timber can still look great many years down the track. People just need to understand if you want that beautiful natural timber look you have to put time in to maintain it.

Look at 'Iron Ash'. Its a treated version of what you're after. Don't know anything about it but seen it recently on the web. Overall avoid Merbau as mentioned above, as well as being an imported 'sustainably' managed timber.... Use local product's when available as they're manufacturered to high standard's, supporting local job's, companies must meet tight regulation's, etc. unlike other countries....