Since you're in the planning stages, I would highly recommend going with a drilled tank which will make your life much easier
All-Glass Aquariums makes a 120 gallon Megaflow model that looks really nice. I just set up a 90 gallon Megaflow and it couldn't have been easier. I used a premade acrylic sump and added a 10 gallon refugium to it. I also used the overflow kit made for the megaflow which takes care of all your plumbing inside the tank. Just some very simple PVC
plumbing is all that's required. I'd be happy to help out with it once you have a better idea of how you plan to go with it. Just let me know.