I personally LOVE zoanthids. There are so many types that you could really go crazy....all you need to start are small polyp bundles, but from there, with some patience, you could really fill out your live rock to look really nice and very colorful. Mushrooms seem to take over too much for my taste, although ricordia and spotted mushrooms are really nice. I've been limiting my striped mushroom growth but have let the spotted ones really come out nicely. I also picked up a ricordia yuma rock a couple weeks ago and it's really cool looking.