I was trying to bite my tongue, but I have to say it.
3 is plain nutso.
I have a 660 inwall display with a LARGE dedicated fishroom and another larger dedicated dry storage and workroom behind that. Both rooms (together are larger where you are planning on putting those 3 tanks.
You won't enjoy those 3 tanks the way they are arranged. Go with a Giant L, or a T, or hell, even a peninsula. If you want FO and Reef you might get creative and put a divider in to separate the biotopes. I personally would either pick a 1 (Fowler or Reef) and concentrate on that. It takes a TON more time and monkeying that a freshwater setup. I spend hours a day on mine.
As far as depth, mine is a 30". I can barely get to the bottom of it without a snorkel and mask, and I'm a big guy. If I need both hands in its mask time. Keep this in mind. Also keep in mind that when its mask time you have to have enough clearance above the tank to fit yourself. I regularly climb up and lay on the top of my tank if I'm doing serious work.