I think I have settled on my 55 setup, or at least I have my wife's approval so far.
We went for petrified wood, in the zen fashion (leaning at 45 degrees). Half the tank is rocky with some slate caves, the other half is driftwood and bogwood. I have close to 60 individual plants scattered around as well.
The captive family will include mostly livebearers like swords, guppies, and endler's livebearers so the hard water isn't going to be a problem.