White pom-pom xenia, short and fluffy, good for the areas, that need brightening. Better place on top or isolated rock - will spread, just as GSP. May grow like forest in the back wall.
Green star polyps - looks like lawn. Placement - on separate rock or surrounded by small rocks - will spread. There are different shades of green - the rare one is really neon-green.
Center or side piece: may be yellow leather, the bright one, hairy mushroom (bright green base, tan-pink "hair"), sold of quarter size, grows at least 6" (15 cm) wide, tolerant to low light.
LPS (out of topic, but can add color to tank):
Red tubastrea (if available), scolymia - bright red or green, grows at least 8" in diameter, neon-green candycane - grows in almost any conditions, very colorful.
As I see it: small forest at the top on one side, patch of lawn - down the hill, 1-2 big pieces, drawing attention, bright spots (like red mushrooms, tubastrea and green candycane) - here and there, to fill the space.
If you plan to have sps, xenia may not grow well in very clean, nutrient poor water.
