Lots of different "classes" (educations) with different bonuses and related organisations for your children to run off to. The general expansion of roleplaying depth due to stuff like birthsigns, bloodlines, artifacts and other additional traits. Generally I find it can make for very interesting CK2 dynastic management on a small scale, even putting aside any interest one might have in the setting.
The magic can be interesting too, even though only the player can use spells right now. It allows you to tweak a lot of things, if only slightly: your character's statistics, province and realm-wide modifiers and so on. There are several ways to become immortal, which coupled with the presence of the long-lived elves can make for some interesting dynamics you won't see in the vanilla game or most mods.
In one of my games I started off as an Altmer with every bad stat that can be healed. Took until I was about 30-40 years old before getting married since I was blind, mute, tongue cut out, etc. By the time I was fully healed up and regenerated my stats were pretty crazy (60 martial, 80 learning, 30 intrigue/diplomacy/etc). From there I became immortal and started a rebellion. By this time as well I had given a lot of the territories I conquered in Alinor to my kids and then set off to conquer Daggerfall.
This is where it became tricky and challenging. My goal was to have no elf rulers in High Rock, only Bretons that are part of my family tree. If you don't convert to the eight divine religion this can be very challenging (I've played a game where I converted High Rock to Auri-el and it took a while). Anyways, I would take a grandson with me to travel to Daggerfall and both of us would convert to the native religion. After a couple hundred years all of High Rock was controlled by my family and they were all Bretons with me as the only Altmer ruler. I'd eventually give the title of High Rock to one of my kin and start the entire process again in Skyrim with Nords. It's a bit challenging at first because you have to find a Nord that would breed with a Breton and produce a Norse 'graphicalculture' child.
(Added bonus: I married my kin into the Orcs so that they were part of my dynasty and kept them alive and well in their native territory. Converting them is possible, but not easy.)
There was also an event that happened to me when I traveled to Daggerfall giving me the Amulet of Kings. That was cool and made creating the Empire of Tameriel easier. I believe the only races I couldn't have as part of my kin were the Khajiit and Argonians because of how they're set up. It was very fun to play in this way, watching my entire family become Bretons, Nords, Imperials, etc, but all coming from a common Altmer background. I don't think I've had more fun with a CK2 mod than I've had with EK.
Another challenge in this type of gameplay was to keep the bloodlines alive but as part of your family. So I'd marry a kin daughter to a Reman (or some other bloodline trait character), and their kids would be part of my dynasty and I'd give them titles to keep that bloodline alive. Of course, some will die out, but it's fun to see if you can do it.