May I suggest a cap of your pavers on the wall and the a slightly darker gray that relates to the privacy fence beyond? That way horizontal surfaces and vertical surfaces show similarities and blends/blurs the separations?

Teal? Just a thought sometimes I think it's smart to match or atleast go with the curtains you'd see in the window

Thanks for all the great ideas everyone and sorry I didn't explain the polycarbonate a bit better :) This is along the lines of what we'll be using... http://www.psp.co.nz/building-brands/corrugated-sheeting/suntuf-polycarbonate The area is an absolute sun trap and we're hoping to use it as an extension to our living space, especially on rainy days! I've just sent my husband out to get a few pots of different stains for is to try - darkest brown (cedar) and a lighter brown (rustic oak) both by Cabots + the black we already have. Hopefully we can decide between one of those! I probably should have mentioned we will have black aluminium pool fencing running along the top of the second retaining wall - so the real question is do we keep everything black (pool fencing, horizontal fence, retaining walls and pergola) or do we go with a dark (or even light) brown for the pergola and retaining walls.... We just keep going around in circles at the moment. Decisions, decisions! Thanks again :)

I don't know how hot it gets in Auckland in summer (I've only ever been to NZ in winter!) but if it gets hot, then go for a pale colour. Dark roofs should be kept for cold places!