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

The house is fairly small from the photo but elevated on a basement or garage plinth. If the base is brick, leave it as is. But whatever colour you chose, eliminate contrasts so if, say, a soft French grey, paint the walls, window and door joinery and roof flashing the same colour. A contract could be the new deck rail, but I would even consider painting it the same colour as the basement to link the 2 levels or just the same as the top. A bright glossy front door could break up the monotone.

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....

Got my answer - non combustible material such as, natural stone - marble, granite or concrete etc.