I think that the problem that you have is that you have too many flat surfaces and angles with nothing to lead your eye away from the blandness. You have grey concrete, grey roof, grey walls and the emotional response to that is a feeling of flatness and blah. The only thing that brings any kind of relief to the view are the plants and the steps that introduce different levels. My suggestion would be to look at adding texture, different levels for contrast to the flat surfaces and colours that unite those elements. Take a look at how the red lid on the rubbish bin pops out amongst the muted tones. Maybe bright red pots with taller (and healthier) looking plants in them on either side of the bench with a textural artwork or screen as mentioned above in between. You could be really bold and paint the steps red!, but don't do the pot plant suggestion if you do that. Once the air conditioning unit is removed I would put more boards down the front to cover up the gap and dirt underneath the pot plants. If you have the available space in front of that, place some seating and maybe a table, perhaps toning in with the grey tones but with a colour pot or cushions that tie in with the plants in the coloured (I suggested red, go with what you like) pots. I would also like to see what sort of door you have to access the room and yes, put the bins somewhere else if possible, they are unsightly.

First time I have ever said this sentence: "That toilet roll holder needs some pants"

Hey, whatever makes them happy. Maybe they have really fond memories of The Magic Faraway Tree. Much as I wouldn't design it into my house (even though my cats would think it was totally awesome), I think its quite cool, in a weird kind of way.

The ‘fringe flower’ is fab,mine is about 1metre x 1metre and the flowers are beautiful, Same with the ‘emerald lustre ‘ I trim mine lightly and this keeps them looking great, would look wonderful amongst the trees you are thinking of planting.