I'm probably going to go ahead with the 24v setup. I like changing things around an experimenting with different configurations.
Lugging 6 batteries around and maintaining them is a pita, plus it's difficult to keep them fully charged. As for the 12v issue:
The biggest 12v draw is the furnace. The furnace runs during the day when the sun is out and the solar is operational. At 7a my solar can handle that even on the worst of days. Other draws would be LED lights, water pump and refer on gas. No big deal. Yes, that bank will draw down slightly, but don't batteries recharge as needed on their own?
Hey, at least I'm not using 6-6v batteries to make 24v! (which is possible)