I always stand up to start with!
Seriously, though, it can be done very effectively. Sedum walls, climbing plants, hanging baskets and pots, plants planted above and trailing down. One advantage is that you can paint a living picture and stand to look at it. What is the situation?

Do you mean the current fashion for living walls?
I have to admit I'm not particularly keen on them as it seems an excuse just to put plants on their side. However, when Monty Don looked at gardens in France, he visited the designer who started the idea, and he was using plants that naturally grow in that position, so it looked pretty good.