After my last post, I did not expect to go this long without some sort of progress... So, I am poking around the 'Net for inspiration and appropriate miniatures.
As 15mm seems to be riding a new wave of enthusiasm, miniatures will not be too hard to find. So, the key for success will be in the rules. I am thinking that Impetus is not quite the set for me, and I am therefore looking at replacements. DBA/HoTT are good candidates, and well as Chipco's Fantasy Rules!, and maybe even MAYHEM. Each has its good and bad points. I prefer the basing of the latter two - they use 40mm squares - to the WRG style, but DBA/HoTT are played locally on a regular basis.
It is still my plan to make historical and fantasy armies, maybe even set it up so they can morph between the two genres as appropriate.
Nothing is set in stone yet and options abound. As the budget for this project is at $0 for the moment, I intend to write up an actual plan and see how that goes. Might even bring the lovely wife into it as well with her own army...