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 :)

It depends on the species of wood (I.e. How hard or soft) and whether or not the ambient temperature can remain as stable as possible. What you caulk and paint in warmer weather may look great now, but when it begins to get colder, the wood begins to shrink, and the caulk will begin to pull away. This will look worse than if you didn't caulk at all. My suggestion is to use a caulk like the brand called "Big Stretch " in an attempt to avoid this.

My vote is for the wash but not in bright white and after some selective knot primer in the same tone. You are going to want to selectively primer down about 2/3 of the knots (use a dark white tinted primer), and use a dark white / brown toned off white instead of bright white so the beams still give you dark white on bright - that would be my vote. Consider something like bm stingray tinted primer and wash on the beams. You can add glaze for more working time or put down dropcloths and use water to cut it into a wash. Test it on some other raw wood that has had tannins develop for a few years. Then put it against your white wall - your husband will get the contrast and wood grain but you'll get the quiet palette you were hoping for. They both will have architectural depth and interest.

You are correct the place does and always will look a bit sparse when you only have blinds. The question with curtains is sometimes dependant on what climate you live in and I am not sure where you are so I am going to say. If you need curtains for heat go for a quality curtain to the floor with a fabric that is not stiff (as I discovered I now own after buying curtains off line for my spare rooms). The expensive curtains I brought for my living room have a softer texture and hang so much nicer. As I need Curtains / Roman blinds for heat I have backing fabric etc on the expensive made to measure ones, where as the cheaper ones are just thermals. If you only want to add a curtain for looks and do not require it for heat I would recommend going with a lovely sheer / half see through fabric that drapes really well, this will add a point of interest and you can colour match or add a loved colour to a bare - white on white - cream on cream - colour scheme.