Well, for the house I'm in now, we want a 55g. I would design my own stand (My grandfather is a carpenter...I'm so spoiled.) and it would be probably brackish water, as it would be home to many different types of Mollies, and all plants would be live.
Once we have our own house instead of apt, we want to have a 100 gallon bowfront freshwater for the basement. Turn the old 55g into a saltwater with Nemo (clownfish) and Dori (that really expensive tang) and live rock.
The living room would have an approx 45 g corner tank with bright colors, but freshwater.
And in our bedroom...I'd love a tall hex, though fiance isn't fond of the hex's so that may still be up for debate.