Good soil + strawberries and herbs + pig face + myoporum purpureum + succulent/cacti + paint a beautiful colour (with excellent surface preparation). All and any of those will take interesting but ordinary, which you currently have, to gorgeous and eyecatching. Go for it! May the force be with you! ;-)

lucky you! your water tank is below ground. I have to look at my 20,000 litre tank outside my kitchen window. It sits on a concrete plinth so I can't even plant around it. I'm too terrified to grow creeping fig on it incase it affects the integrity of the tank. At the moment it has wisteria draping over it, looks lovely in spring but deciduous and it's now becoming too invasive so need to get rid of it.. I also have star jasmine approaching from an arch beside - can't wait for it to take over the tank.. I love all the decorative features suggested but I reckon something like star jasmine might work with some other landscaping features to the side: bench, rock, more plants. The beauty of star jasmine is that it doesn't root, will drape over and can be pulled aside. Every couple of years I put the blower over the top of my water tank it to make sure the leaves don't mulch to create soil on top.

Yes painting is not a task I enjoy & think the concrete is probably best left as is - with the exception of a good wash.... that being said .... I can almost visualise the building now with black/charcoal windows & doors & lots of mass plantings creeping up to the concrete & now feel the dark growth on the concrete might just serve to pull the space together with the help of a structure overhead. Hahaha listen to me... I've gone from hating my concrete to almost defending it :) Siriuskey could you try posting the link again please as it just goes to Google home page? Or even a search topic & I'll try to find it. Thank you all for your suggestions & hopefully I'll have an updated image to share sooner rather than later.

i would be surprised if the floor under the old verandah is properly constructed to avoid dampness and "raising the roof a little" and adding footings just under the doors is not as simple as it sounds ... i would have a builder check to make sure that the preparation is done properly before considering the bifolds..no point investing in expensive new doors and internal new finishes if the floor is likely to be damp