Looked around a little, didn't find a discussion on it so stop me if you've heard it already or even implemented it and I just didn't notice. So my personal naming convention for units is to use just the unit's type name. Once the unit's promoted, I add a descriptor based on that promotion so I can know the unit's combat role at a glance. Managing my units via role seems to make me far more effective as it pertains to military matters. For instance, a Musketman with one or more city defense promotions would get renamed to "Garrison Musketman", add in a strength promotion and I make it "Elite Garrison Musketman". Admittedly, it sounds like it would be a total pain to code.