No those wouldn't work at all. You see, since you are keeping discus, they really require things to be done differently to keep them from getting sick. Most people seem to keep them bare bottom, glass only, with some plants on wood or in pots, sitting on the glass. See my tank pic in the Photo Gallery here, "My 1st picture here" from a couple weeks ago. See the tank bottom? This is done to make it easy to keep the tank bottom clean. Discus make lots of large poo, eat lots, and there is a lot of waste produced everyday. This waste and uneaten food will just collect in the large gravel,or rocks, where they can't get to it and neither can you to clean it up. BUT you can have substrate for your large and beautiful plant collection you want. The plants will grow well in the sand, and all debris will sit on top of the sand where you can easily vacuum/siphon it up. Your tank and water will stay quite healthy. You can look through the pics in the photo gallery and see lots of tanks with sand and plants and wood. Look at Chad's tank set up in the Discus challenge going on here. He can tell you all about setting it up.
Barb