wtf? ipranges from 10-scope are not enough for you?
how many "divisions" you actually have?

may I ask, just for curiocity, how do you apply those IP's? do you have dhcp's in all of the offices?
just trying to think how IP identification is better than just pure groups.
if done properly, they indeed can provide usable information but in most cases they are set in non-special fashion and thus do not provide any advantage over grouping.