In my completely biased opinion :p, make a frag tank! If you are just looking for something simple (and to scratch the itch that is saltwater tanks) you can't go wrong with a frag tank. Often one fish like a lionfish can get boring, and upkeep and maintenance can be rough with a fish like that in smaller tank.
With a frag tank, you can constantly fill it with new awesome acquisitions, and if you are good to them, you get a lot more back from it then any other type of tank.
But then again, i'm totally a coral guy.