I like the look of a wood stand - especially if you are going for an "island" tank visible on all four sides. To make it universally accessible, try using Magnetic Catch Latches for all four wall panels - instead of hinges. I used them in my home behind a built in home theater rack. They work great - holding up 3/4" thick MDF panels 6 feet tall and 2 feet wide - and I wish I had them on my aquarium stand. My finish carpenter bought mine at a local hardware store - but these look similar:
Just make sure that the resulting corner posts are sturdy enough to hold all that water and rock. I am no engineer, but I am guessing the sidewalls will often add strength to the support system.