Well if by saying aquariums your thought of a glass aquarium.. Thats generally not the way to go. Some reptiles do fine in them depending on size.. But for igs you want hight and not even my 150 gallon tall fish tank is proper for a 1-2 year old ig.
I typically suggest to people a basic plywood cage. This will hold in heat and humidity and be easier on your bills. If you are in like cali or florida its generally pretty warm there most of the year you can consider something like a PVC cage.. I dont use those unless it is nice and sunny - in the summer.
IMO an adult sized cage should be as big as you can make it. Almost to the ceiling line of your room minus room for lighting on the top and a little extra to make sure you dont burn the ceiling. :) Plywood sheets commonly come in 4x8 sheets if you can make a cage that is 8 foot wide.. I would. Just 1 piece on sides, 2 on the back and the top/bottom 1 sheet.. Pretty simple. And just adust for height. Typically for an adult ig I suggest 4 foot depth, 6 foot width and at least 6 foot height. You can use some basic 2x2's on the inside and frame it all around the sides and inner corners and add strength to the build.