As long as as it's cycled I would get a small cleanup crew that you'll add on to later and some mushrooms. I also get a xenia because they grow like weeds and I wanted to see something grow in my tank.
I like that I started with a cleanup crew because it adds movement to the tank and yet not much of a bio load. My two mushrooms have grown about 25% since I got them 2 weeks ago. Depending on what kind you get they can reproduce pretty fast also.