I have been considering all of this stuff myself, as I just bought a house and am planning on upgrading from a 90 to a 150.
I generally felt that a 150 gallon was too much weight for my living room so I made the choice not to buy a place without a basement with a bathroom in order to accomidate 1500+ pounds of weight in a 72x18 inch area..and still be able to easily do water changes. the tank is 72x18x29, so its a lot of concentrated weight..
my mom thought I was crazy to buy a house with the provision that I could accomidate a 6 foot very heavy aquarium but I told her its my hobby! LOL