Juvenile discus are a little tougher to keep than adults, and generally won't grow out to their full potential in a planted tank with substrate. All the discus breeders I know (I attended a discus convention a few months ago and have some club friends locally that breed them) grow out their juveniles in barebottom tanks with multiple daily feedings, and daily water changes of close to 100%. Granted, they are keeping and breeding show quality fish, and not everyone is into that, and that's ok. But the results speak for themselves IMO. I've tried to grow out discus in a planted tank a couple of times and they always stunted.
With adults, you can cut back on the water changes to once or twice a week, and they'll generally do fine in a planted tank. Of course, the adults are much more expensive to start out with than juveniles.
If you decide you want to give discus a try, I would strongly recommend getting them from a quality source, as they will be easier to keep and less prone to health problems. The discus you see at the LFS are typically not good quality fish. There are lots of sources for nice discus- Kenny's Discus and Discus Hans come to mind immediately, but there are more than that.