Wow this a really good thread....!
Two things occurred to me while reading all of the posts.
1) That regardless of size, you are either on your way to a monster tank or planning your next monster tank. In ther words, as many have said before, it is a state of mind that will result in a natural progression to larger and larger tanks.
2) That regardless of how "large" the fishkeeper's imagination is... there should be a basic standard of what is a minmum size for a monster tank designation.
Personally, I have a 125G, in my office which has a 55G sump to make water changes easier and I maintain a 110G that I set up for my mom. Today, I do not consider any of them to be monsters tanks.
Also, I race large sailboats... 35 to 66ft. In sailing we have something called a "Maxi" which is anything over 80ft. For boats between 58 - 79ft there is a range called a mini-maxi. Of course then there is the Mega yacht which I believe is anything over 125ft...
My point is that there is a standard...
Maybe < a 125 is a "nano monster", 125G + is a "mini monster", a 300+ is "monster" and 5000+ is mega monster...
That way they are all monsters... just different degrees of insanity... opps I mean obsession,,,, damn... I meant addiction..... well you know....
There was also a post about 2 out of 3... I think that could also be a good start. I'll go back and find it...
mm