Hi from Australia, and welcome to Simply Discus.
If you are thinking of setting up a tank, have a good look through our beginners section, where you'll pick up lots of good information. You will see how they like being in largish groups and how regular water changes helps them grow to their full potential, and more importantly good health. Its really up to you, and what you seek from the hobby.
Its great that you've had some experience in the past with discus, and if you have any pictures from then please share. I like your dream of hopefully having a huge built in tank, and the way you have described it paints a pretty picture. Good luck with that...Dreams can come true