Quoting Mhantra:  

"Many of these take a lot of work just to open them up in the research tree, so there is already a control on them, but perhaps make them their own timer, not connected to a town, but maybe make it have a longer timer to build, or have some other limitation.  It is a good system, just overwhelms the city building queue, especially since you usually have only a couple cities nowadays, so there can be 2, 3, 4, once I had 6 outposts governed by one city."

I fully agree.  I use high towers to grab resources and really nothing else unless I see a big bad army/monster heading for a particular area, then i will try to build an abbey and the offense/defense upgrades...

Please adjust the research tree, so many things that would be more useful in the mid/early game don't pop until I spawn a dragon or too...

Sometimes use the High Tower upgrade to get connectedness (reduces unrest in cities).

rarely use the warden upgrade.

Never use any of the other upgrades.

I think the upgrade options are not fine.  To me I  have not seen it be worth the time and effort to build them or research something based on upgrades.  Upgrades have had no effect on my choices to research.  

I will say other bugs, bother me with the game.  One is the fact of monsters ignoring other AI scouts/pioneers/outposts/city.

Outpost need to mean something, rather than just spam for resources.  

I use them from time to time, especially when I can use them as choke-points to give all my units defending the area bonuses.  I have also used the bonuses to help my army defeat particularly difficult armies, such as dragons.  With large 5 unit armies, the bonuses are fairly substantial.

My problem with them is that they simply don't make a lot of sense.  Why does the area around your outpost only get the bonuses?  Shouldn't the area around your cities get the bonuses as well?  You would think that a populated city would generate more bonus than a remote outpost.

Also, why doesn't the AI build the upgrades?  I have never seen the AI do anything other than place an outpost.

With the above in mind, I would propose something more logical.  Tying the current bonuses to either existing buildings (e.g., you build the shrine and you get the reduction in cost to tactical spells) that can be built by every type of city.  In the alternative, you could just create new buildings unlocked at different tiers of research that are buildable by all cities that have the respective outpost bonuses.  Under either idea, the area around the respective city AND each outpost tied to the city will get the bonuses.  This should also make it easier for the AI to get the bonuses.

A final alternative would be to even the playing field (with the AI) by simply getting rid of them.

One last thought is that some of the upgrades would be nice, if they actually worked.

I'm not sure the warden works on enough mobs, especially in LE, given that I rushed a warden on an Arcane Monolith next to a wildlands area, and all that seemed to do was draw the mobs out of the wildlands and into the outpost area.

Wonder if that should be pointed out in the description, or is it, I haven't read the description of that in-game in forever.

I usually forget about upgrading outposts because they are disconnected from your city building queues.  Once I remember, however, I usually put in stables for the faster movement.  If necessary, I will use High Tower in long empty expanses to reduce the number of outposts needed to get through an area.  Occasionally I will build a Consulate if growth is really bad.  The rest of the upgrades I leave out because they are so limited in their area that they are not worth it.  They only work in extended battles along a static front or in chokepoints.  As soon as the front moves, your investment is rendered useless.

I would like to be able to have a stable-like effect within a city's ZoC without having to build redundant outposts within the ZoC.  Either automatically grant stable effects within city ZoC when you research the tech for stables, or have a city-buildable stable.

I also have thought about some sort of road building upgrade that will connect the outpost to the next nearest city or outpost, or upgrade the road to a better, faster version.  This is particularly an issue when you capture enemy cities and your road building tech does not automatically connect them to your empire, or when it autobuilds roads through another kingdom instead of around.  You have to play connect the dots with outposts to try to bring the endpoints of your roads together to get the roads where you want them.  You usually end up with a gap between two road systems where there is no road at all.  Something like a road level for each outpost, starting at zero, that you can upgrade.  The road between two outposts would be the lowest quality of the two endpoints.  Another option for "New Roads" that would tell the autobuilder to find a path to the next nearest faction outpost or city within a certain range where the travel time would be reduced by more than X% by a direct road.  (please also devalue building roads on lairs and quest locations)

I would also suggest the option of linking an outpost to a different city instead of just the closest.  This would allow you to direct resources to the place you want them (grain, materials).  Perhaps with greater building cost the farther away the outpost is from the city.

Another suggestion for outposts is to have pioneers build them, but instead of being used up, have them teleport to your nearest city and be immobilized for 10 turns.  (i.e. they take time to build the outpost and then return to the city for new supplies)  The 30 pop cost for a pioneer doesn't make sense for the building of an outpost.  Especially when Pariden can plop them down so cheaply with Arcane Monolith.

Possibly the best suggestion yet! Nice thinking!

Perhaps let heroes construct outposts for gold and any upgrades would cost gold but either be instantly completed or let the outpost construct the improvement by itself (fixed building times for each upgrade)

Because of ZOC overlaps, i would like to see the ZOC for an outpost highlight it when I click the outpost.

This would help my "outpost chain" and increase my use. I discovered outpost spam can and does work with arcane monoliths but you have to commit to the strategy or it fails the moment you stop your commitment because you won't have a city in your spam-zone to rest units in and rush new defenders if you have to.

I don't ever use the upgrades.  Always something better for my city to do than to do upgrades on an outpost.

Most the upgrades have military use, but most combat does not occur around them. If outposts were expanded upon, I believe they could serve the game better. 

Make them more like you would expect from an outpost and not just a tower you toss up to expand your ZOC. Give them their own build queues and have them be semi-blocking. Invaders would practically need to deal with your outpost (if garrisoned) before heading further in to your territory and attacking cities. Wars would focus more on your outer defenses, a perimeter of outposts strategically placed. 

That would kill prioritizing strategy and make the game poorer in my view. The only strategy then would be when to research the tech needed for the upgrades. Good strategy games are about hard choices and priorities.