Another very important thing to think about is where the tank is going to be and how much weight can your floor support. If your tank is going to be in the basement, go gung ho
and go as big as you want, the cement slab will hold pretty much anything, but if your moving up to the first or second floor, you may want to consider re-enforcing the floor supports if you go over 75-90 gallons. The typical 125 gal
aquarium weighs around 1400lbs filled and a 180 gallon aquarium weighs in at 2100lbs!
Just a little FYI, don't want you to fill it up then hear a loud crash in the middle of the night as the floor buckles.