I don't know what kind of filtration you've got, but if you want to try a foray into SPS, good starters there are pink or green bird's nest and Evil Mel's Green Mille. None of those require HUGE amounts of light like a lot of SPS and are more tolerant of slightly off water conditions. I've kept all three of these in my tank even years later because they keep their color well, grow fast, and I can still sleep easy at night.
If you're looking for other LPS I might recommend Duncs. They've come down in price quite a bit, are nice looking, and are relatively easy IMO. There's always frogspawn. Been some pink and green floating around the club that is real hearty. A lot of LPS are fairly slow growers, but frogspawn puts on size pretty quick.
I've never found zoas to be easy to keep but a lot of other people have a lot of success with them. My only recommendation here is to talk to find ones you like and then talk to people about their growth. Some zoas seem to never grow much and others can actually become more of a pest than anything.
