I can think of three ways to make your gameplay experience more fun:

1. Create an AAR.
2. Download Myrddraals "Hotseat mod", which allows you to switch factions. So halfway through the game, if you have 30 cities and are owning everyone, you can switch to a weak faction, and with that faction have to face your former empire.
3. Again, download Myrddraal's "Hotseat mod", and play a multiplayer campaign. I've got one going right now, it really makes the world seem less empty, knowing you aren't the only one on the map with brains. This, in combination with creating an AAR, is working for me.

You can download the Hotseat mod here:
https://forums.totalwar.org/vb/showthread.php?t=64876