Here's a handful of ideas that I have about making the gaming experience have more depth. Apologies if anybody has already thrown these out somewhere, I don't recall seeing them mentioned previously.

• Don't unlock magical and legendary armor (and weapons/equipment for that matter) just by researching the tech (not even for purchase in the Shop), require the player to also build a Wizards Tower or Forge, and/or have a Hero that is a Caster\Smithy stationed in the city. Heck you could even base the equipment's effectiveness/stats on the level of the Caster or Smithy that you have.

• More variation with what is available in the shop. I'm finding that I don't care for the "global" nature of the shop when you are in your territory. Something more along the lines of Shop items depend more on the closest city, with some randomness even:

1.  
   1. Just randomly remove some available armor, weapons, equipment for several turns due to natural variability
   2. "I'm sorry My Liege, we don't presently have Elementum available for the Legendary Shield"
   3. "We are expecting a new shipment of War Horses very shortly"

• Teleport ability to areas outside of your territory (at a much steeper mana cost). Range/Mana can be affected by number air shards controlled or something.

• Nerf the Dragon/Demon recruitment. Not the units per se, but the number. Make the recruitment number, time, and cost more commensurate with the combat rating provided.... this is probably mitigated some if a stacks combined attack and defense has been reworked, but regardless, I don't really think an army of young dragons running around late game is what was initially envisioned...I certainly didn't.

[EDIT]

• An alchemist technology and building (or some such equivalent) so that you can transmute resources (e.g. 2 metal -> 1 gold; 3 gold -> 1 crystal, etc.)

Here's a couple ideas I saw mentioned in the forums that I really liked, apologies to the OP as I do not recall who deserves credit:

1. Allow higher level Heroes to be recruited from Pubs and Taverns once built. 
2. Allow Some quests to be given/started from the Guilds, Taverns, Pubs, Minor Races