I park them in cities only near the end-game or if they happen to be near a city and I need to build a unti for them.  In the latter case I park them until they can travel again.

More than anything else this particular concept is where the two different parts of the game RPG Adventure vs Civ building are exposed as not being 100% connected yet.

I do.  Really useful once you start conquering.  I prefer to get them research upgrades if possible.

SOme of this is due to heroes being UP right now, but some isn't, I did this in FE as well.

Injured heroes will become admins.

I think as a "path" the stationed commander is in theory pleasant.  I get annoyed when I have too many Heroes at the moment because of the exp reduction when many of them are in the same unit.  In some sense, having a stationed hero or two helps me to enjoy having fewer to micromanage but still gain a benefit from them.

It might be worthwhile (but OP?) to consider traits that allow them to gain additional exp sitting in a town.  Similar to them sitting in a town with an adventuring guild.  Only for any town.

When they get injured enough to be useless, put them in a city.

Typhoid Fever is a good example.

I don't use them for the exact reason that was said in the OP. The administrator needs to stay in cities while leveling up is outside of cities. So you take administrator that gives you like, 15% or so reduced unrest in the city and that's it. Your empire grows, unrest grows, one administrator can do so little later in game. If you take more then one you are significantly weakening yourself by limiting your fighting heroes. Basically, the problem is that there are almost no ways for administrators to level up while doing their job - administrating. This, i believe, should be addressed by giving them way to level up in cities.

The concept is good but implementation in not. Heroes are not common enough to where shackling one in a city makes any sense. They are far far more useful in the field, fighting/exploring and earning xp. There should definitely be dedicated "civilian heroes" (DLC!) that are separate system from the combat heroes so you dont have to choose between the two. Id make mobility the defining trait of the civilian classes.

So like

A Bard' has the strongest bonus but it only last for a few turns and then they need to go to a different city before they can reactivate it

A Lord cant leave the city they settle in

Merchant Guild moves between random cities for random amounts of time

Retired soldier have the weakest benefits but only need another hero to escort them if they want to move.

I love to have leveled administrator to put into conquered city until it build Bell Tower, Town Hall, Cleric to become useful. Without help, conquered cities hardly do anything.

ok so, same problem as before.  administrative heroes are still useless, basically.

we need heroes to be able to gain some administratively related xp while governing a city. The exact numbers can be tweaked so that it's generally weaker than adventuring, but the concept has to be there

Never use them. (FE)

I never take that class intentionally.

Even if one is given to me:

Early game I'll ignore the in city bonus bc I need my champions to lead my armies.

Mid to late game I'll dump them in some city and forget about them bc I don't want to be bother with trying to level up a worthless champion. Annoying that if I get unrest in a city to 0% their bonus isn't helping any more. They don't make enough of a difference to be worth micro fussing. There is a similar issue with buildings which lower unrest in that some of their benefit is wasted. I despise the unrest mechanic, this is just one of the problems with it.

Rescuing the governor concept

In my opinion LH should make governors completely separate from regular champions. You get them at certain fame levels, not as a replacement for champions but independently (if everyone gets them they will use them and governors will become another aspect of the game). They only live in cities, can fight in city defense but not adventuring. They level over time at a fixed rate. Their power becomes much easier to balance bc they can't go adventuring.

Why a fixed rate XP gain?

Because simple is better than complex. Nobody likes xp tied to fighting (current system). Other suggested systems gain xp though city defense and through building things/training units. Effectively, these systems would equate to a fixed* rate xp gain. To the extent that they aren't (city defense xp) the effects seem perverse: is micro moving your governor so they can fight in every city defense fun? For governors I can't see any game play benefit to tying xp to anything other than time- though I'm open to explanations. If governors are bound to cities as a non-landscape way of differentiating cities the mico- worries would disappear, and I could see a time + cityDefense making sense but cities aren't attacked over and over again so I don't think this would make much impact on overall xp growth.

* In any game your cities are always producing something. It is true that each level require more xp than the last. This is mostly done in games to balance giving more xp for harder monsters, could could be done differently for governors  As cities get bigger they produce more stuff. It is easy to imagine these numbers being out of whack, and any system actually used would alter the numbers until a desirable normal play level progression was achieved- which since your cities are always building something would end up linear which is why I say fixed.

To make a fixed rate xp gain just make it that each class gains 1xp per turn regardless, think MoM here.  I know this is a discussion for governors but this simpleifies the equation such that everyone is gaining experience even if they are just sitting administrating.  However they gain it faster adventuring.  Also you could then add a bonus to some building like a town hall that then doubles xp gain while stationed in the city thus making it worthwhile to park administrative types but still allowing them to advance.  Keep in mind 2 xp a turn will add up initially but in the end for a non combat centered class its not much.  To counter the free xp just bump up the xp table higher slightly (maybe 50% at most) and you should have a stable reliable system for managing xp.

Sorry if this is not clear, not much sleep the last few days (school).

+1 for endless space way. found the concept work well in this game. Each city can get an administrator who get xp for each production?

In legendary you get lot of heroes that do nothing, personnaly I can just level 1-3 armies (and that cost lot of money), so even when you get nice heroes later you just don't level them... Administrators need to be more fleshed out, need different ways to level other than fighting.

I never keep champions in my cities unless I have a reason to defend it from attack in the short term. The issue is that if you park them in your cities you have no good way to level them up (even with the buildings that provide a bit of xp) and unlock new governor type abilities. So if you are going to bring them along to the fights any way you might as well give them fighting skills in my opinion.