Governors also reduce Unrest in the city - so a champion with just PotG will reduce it 5% and then a further 10%.

Perhaps path of the governor should also add xp for sitting in a city? I also think that adventurer's guild building should be buffed, well at least the xp per turn part.

Governors don't really need a slow growing 1 xp / period.  A better way to level them up is to take them on quests as part of a stack of heroes.  They don't dilute quest experience like they would clearing normal monsters when stacked with other heroes.  This only takes 10% of their time and a few quests soon makes them a lot better than a basic level 4 governor. 

In my recent game I bought 5 quest maps from a neighbouring Altar city (costs 100 gold each) and with tutelage levelled my heroes up.  My governor is now level 8 and has Loremaster 2 and Administrator 3 and Road building (very useful).  Loremaster 2 gives 3 research per turn and Administrator 3 means he can quell 65 unrest (5 from hero, 15 Governor trait and 10, 15 and 20 from Administrator 3) which means he can handle nearly all the unrest in a newly conquerred city on his own.  That saves a huge amount of gold that is normally used to rush buy cleric, bell towers and town halls that the AI seldom builds enough of.  You can also take them on quests that kill the boss monster in wildland areas (like Torax), they can build a road as the killer stack of heroes makes its way to the boss.

So governors are very useful in several different ways and not too hard to level up if you think about how it can be done.  They don't just have to sit in a city all the time although they do help boost a new city up to level 2.

JJ

I will commonly give a governor hero a strong army and level them up quickly, then plant their butt in a city for a long time. 

I find that a smart solution but situational. You need to play vs altar AI, and them be near of you. Or spend turns sending someone to buy the quest maps. Other solutions to level the governors is send them to "standard" quests, or give them an army and go to some wildlands. But that will probably take more than 3 turns.

Again, you must move them out of the city to let them earn XP. One more thing: roadbuilding. A usefull skill, indeed, that also takes them out of the city ...

Loremaster and merchant are pretty weak too. If they gave a bonus to city research/gildar instead, that could at least give a boost to take into consideration. That would justfy to have one or more governors, and take some time to level them up. To be usefull, would mean that they should not move from that city once leveled, but at least, the bonus could deserve when stayed in a developed conclave or town. A noticeable increase in gildar or research could really offer an interesting alternative for that path. And a new trait, something like "Engineer", that increased the production of the city he stayed, could be also a good one to take in mind.

As randomness rules, having the chance of getting any one of those 3 traits, and/or administrator/roadbuidling (those 2 are the only usefull currently imo), could be a serious improvement for the path.

I think governors are great for city defense -- if you ever have a need for an army to garrison a city, a governor is not going to make that particular situation worse and over time you'll have a better army because of the bonuses provided by the governor.

In a way governors are similar to building city improvements which provide production -- you do not get an immediate benefit so sometimes they are the wrong choice. But if you can survive long enough the benefits they provide can be considerable.