For some added variety, include rocks and driftwood pieces for your fish to hide in.
Things to Consider:
Driftwood is best -- Other types of wood can dirty your water. Driftwood is safe to use and will hold up.
Brighten it up -- Rocks don't have to be dull and boring. There are a number of fluorescent rocks to brighten up your tank.
All-in-one -- For a little driftwood and some plants, choose a driftwood garden that comes with all you need.