Master of Orion 2 had two types of heroes- Governors (who stayed at positioned planets to improve them) and Fighters/Captains/I can't remember the name, the point being these other heroes were on a given starship, improving its performance. I don't know whether it would be necessary to create two different classes of hero, but certainly having attributes that reward staying home to defend and administer things should have some sort of reward!
I think it was governors and commanders.
The thing I like about the more flexible hero/champion system, rather than the split governor/commander systems, is that in peace time the governor-type hero can use her abilities to help her town grow, but in either city defense or in a pinch if no one else is available, she also has martial and support skills that are useful on the battlefield too.
XP for building/training sounds like a great idea! Here are some other ideas for improvements a governing leader might give:
*Improving trade for anything that covers the influence area a caravan may go into?
*A savings on purchases for heroes within the hero's influence area (like 10% off purchases from the Shop), and likewise a bonus to the sale of items in that same area.
*A bonus to prestige for the area visited.
*Decreases to unrest for the area visited.
*Increased movement for troops within the area visited.
*Decreased chance of city being attacked by creatures.
Good ideas, in my humble opinion. But like I said above, I for one am a little wary of XP for passive things like building/training.
Maybe there could be two sorts of trait trees: a governorship trait tree and a martial trait tree? And the experience gains for the two are separate?