Well...is it a bunch of plants? What are you housing within the enclosure animal wise. Depending on what species you are managing will decide what plants you may keep. Some larger frogs will break more fragile plants, and many toads will uproot all but the hardiest of root systems with their burrows. Regardless, from an aesthetic point of view I would say your vivarium needs more color (I know plants are mostly green but work with me here) it seems as though all of them are the same shade. So your bromeliad idea seems promising especially if you got one with the large red foliage. My favorite is to go the carnivorous route; pitchers, sundews and flytraps always make interesting conversation points, and are functional at keeping fly populations low. Of course, you could always go fungal if you are keeping small frogs like darts that wont break the glowing mushrooms. So you have options, just be creative. Plants come in many shapes and sizes, so don't just keep to philodendrons, ferns, and airplane plants. Try some exotics, terrariums and vivariums support them wonderfully, and you'll enjoy your tank much more if you do.