I am a very visual person. If you could post a picture of the area (even if a virtual "blank canvas" I believe we would be better able to assist you.

I envy your being in an area warm enough to do this!

You could potentially grow some on rocks, they can grow like that in the wild. You could try planting them in sort of diagonals to each other, so you have a bunch of different trees interplanted, and the veiw changes drastically depending on where you stand.

You could try making a large central ring, made up of a chain of smaller rings. Each ring would have a centrepiece plant. I wouldn't put the bulbs directly in front of adeniums because they can get long leaves that would cover up shorter adeniums.