I really like the suggestion Modern feature walls. Combined with some greenery inside and out as suggested by chookchook2 , you can start to soften the 'boxy' look of the space which is now reinforced by the line shape and form of the couch you introduced in the updated image. If it is a breakout or meeting room could I suggest, budget permitting, some form of window treatment. Some simple and relatively cheap e-screens would add a degree of privacy, but more importantly remove potentially annoying distractions from outside; important if you are using the room both for work that requires concentration' .. or alternatively, impromptu meetings with others that may be held in the room. I do like the green, but the photo projects a rather drab uninteresting interior despite your efforts thus far.(imho). I think making a call to Modern feature walls should be on your call list. Something has to be done with that ceiling which I find not only distracting but is actively working against your attempts at creating a really inviting space that people will want to break into. I can a hint of a table off to the right in front of the window. The best breakout spaces I've used have the facility to informally and casually sit across a table with sufficient desk or table space to spread drawings, images and presentation ideas. .. It just doesn't work as well if you and a colleague(s) are forced to sit or stand along one side of a table with the yard providing tempting distractions when the focus should be on communication and collaboration. Mounting the TV and raising it would open the room up further and likely break up the 'box-iness' further. .. A bit beyond my field (Window Treatments) ... but you did ask. lol.

Yes - there are these amazing options to have an 'electric pool cover' with a slat arrangement that allows you to virtually walk on it. Do a google search...'pool covers electric'... I've no idea on how much they cost... Here's some pics. Not sure if irregular shapes make this too challenging... Our pool experience... We are needing to change a few things with our pool already - wish we had paid more attention to the pipes and filtration... (Having to potentially move them as they are too shallow and in 'awkward spot'... Extra $ and I'm so worried it may cause issues for us... Even the location of the concrete slab for the pump... Wish we had thought about overall picture... If I was buying a car for $70k, I would have done more research, but somehow we got carried away with idea that we could have a pool for summer, and yet reality is that it's ready for the 'next summer'... Budget plan (original) was around $30-40k, but I guess it's like building a house... Plus it's all a big learning experience...

You never mentioned your budget that you're willing to spend. You could add a thicker fill backed insulation blanket - 50mm, 75mm or 100mm are the common thicknesses. Steep roof pitch so would need scaffolding, harnesses, etc.. which adds up quickly. Probably still not enough insulation though but probably cheapest option. Insulation under existing timber linings then reline over the top of that as some have suggested. Working at height though so would need scaffold set up again and working overhead is not fun nor easy. You could replace the roof with a sandwich panel roof. Try Versiclad or Kingspan or comparable. They have a polystyrene type of insulation between an outer metal roof sheet and a metal inner sheet. These are heat laminated together. Again different thickness available from 50mm up to 180mm is common. The 180mm has a R rating of 4.7 which is quite good. Again steep pitch, etc., probably need new ridge capping, etc.. Probably most expensive option...... Keep us all posted on your decision though!

Thanks everyone for your comments so far. Bowmandrum , I definitely agree you need to tick as many boxes as possible for potential buyers. In answer to a few of your questions, we are in Sunny Brisbane, so the weather is not really an issue. However, our dilemma between a pool and spa is the very difficult access, the size of machinery dictates what we can actually accomplish. Hence, from our point of view it very much is a case of asking the question, if we can only manage a spa - will people appreciate it/want it or is it not worth it. Based on feedback with the poll it looks the spa will be worth the investment.