to add to the wood/plant suggestion, some mosses (iirc christmas, maybe java but do some homework first) tend to not get eaten as readily by fish. They also have a neat habit of having rhizomes (= roots) dig in to softer substrates. This doesn't mean gravel/sand, but rather driftwood. So if tied down for a period, covering some nice surface area, they should take root and grow from the wood.
There is also something to be said for some surfaces with a mature algae. Petrified wood is easy to obtain, worthless for the most part scientifically and make some amazing colors with simply algae. Bone can have this effect too, but as a caution avoid antler. You also want a more sun bleached older bone, you know the kind. Some bones also are prone two two issues. A fungus that makes blobby white spermy looking garbage grow on it (bonus: it smells of poo.) If this happens, the bone is too "young" and still has organic material that the fungus is feeding on. The second issue is that some can, randomly, get eaten by bacteria that harms nothing. They just disintegrate. These also make fantastic homes from various mosses, if tied down first. Some sandstones can make spectacular algae covered surfaces, so can shell if you are close to the ocean and find a good sized chunk. I have seen shales deepen with this amazing deep green color, as well. If someone helps me learn to photograph it, I'll show my tank. I don't actually plant it, but I let the algae do its thing and the Synodontis (I think it's him, maybe) keeps it from growing as wild as in my dads goldfish tank. My dads goldfish tank looks planted, just with algae on the bones/rocks in there. The cow skull looks particularly stunning.
I like Anacharis in ANY tank and really wish hyacinth didn't make a mess of the tank. I also adore duckweed, but I might be about the only person that does.
that's literally the best shot I can make at a planted tank asking for help. I'm rather trash at botany. If you wish, I do have a friend that has a planted orinoco basin biotope that has a masters in botany. I could ask her on your behalf.
