I once saw a gorgeous grey house with a chartreuse door and lots of purple plants in the front of the house. Wouldn't work my (horrible) salmon pink house (one day it will be painted) but since you have the grey might be worth considering?

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

Hi anne, that's what I was originally thinking, my issue is what colour I use for the 'pop' :) I keep coming back to a teal/turquoise colour (it's one of my favourite colours!!), I love blues, purples, teal/turquoise - many on here have suggested yellow but I'm really not sure about it. Here in New Zealand we're in Autumn, nearing Winter so uncertain about the yellow. I found these cushions that I've fallen in love it, and wondering how I could make these work.. do I try teal and mustard together, as an interior designer suggested?

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 :)