Some friends of mine have recently played Kings of War with thier Warmaster armies , they agreed how many bases made a troop , regt , and a horde and went at it , i think they changed from inches to centimetres but they say it gave them a great feel for a massed combat game and all the elements were well represented by thier figures .
Kings of War is a good simple rule set thats gives a good enough game without all the headaches and its a free download if you just want to try it out or an $8 AUS investment gives you the rule book and all the official Mantic lists .
I think this rule set would fulfill your needs sutably well
cheers Tom