This thread is more of a starter for now without an actual decklist in mind. I am just trying to get some of my thoughts written down and potentially get suggestions on where to take this. Once I finalize a Commander choice, I will update this post with the decklist.
As of right now, I am looking at the following Commander options, which lead to different builds:
Cecily, Haunted Mage / Eleven, the Mage - This would be focused mostly on a spellslinger/big spells type of build. I probably wouldn't do a lot with X spells but there are plenty of big spells in these colors (or, I assume there are; I haven't actually looked yet) that would allow for quite a bit of use out of the ability. Plus, the Commander helps keep my hand full which is always welcome. The main concern is that going too heavy into the big spells aspect means I can get stuck if/when the Commander is removed. It sounds fun but can falter a bit more easily depending on how heavily I lean into big spells.
Marchesa, the Black Rose - Marchesa would be more geared towards theft and reanimation. The idea would be around using temporary theft effects and sac outlets to permanent steal creatures. And because it requires +1/+1 counters (which Marchesa helps provide) I would want to add in a few more "extra" effects for that. And because I would be doing things around reanimation with Marchesa anyway, I might make it a true reanimation build with things like Reanimate or Goryo's Vengeance depending on how many Legendary creatures I end up with. This list has fewer failure points as it would be less reliant on the commander since the individual pieces can still be good on their own. Not as good, but still good nonetheless.
None others really stand out. Sedris, the Traitor King could fit a reanimation theme but seems just better in another deck if I want to run it at all. Kess, Dissident Mage and Abaddon the Despoiler also seem like they would be good inclusions for a potential Cecily deck, but aren't enticing enough to helm the deck.
It will probably take me a while to get a fleshed out decklist but I am hoping that by starting this thread I will actually get the list built. In the end, I want to come up with 3 new decks total (retiring at least one current deck) and the three mentioned here (Temur, Naya, and Grixis) are among the leading candidates for new deck colors.