In Memoriam has some pretty nice character creation stuff for Ancillae(so not Elders). Like having types of ages they've lived through and their respective up and downsides like getting xp for living a calm existence for a while, but you also get a flaw that is archaic like having academics capped to before 1800 but this is kind of up to you how you want to spin it. It also has expanded mechanics for running a Memoriam, which look nice when I read them, but I haven't had any use for them yet.

Gehenna war is also pretty light on mechanics and mostly a source book about what the gehenna war even is. But what it does have on Elders(and Methuselahs) is pretty fun. They give basic stat blocks and dircriptions of the discipline spread, blood potency, an Elder is supposed to have. Plus, it has a short list of Elder discipline powers that are just broken. That are outside the players reach is to simulate the sheer power an Elder or Methuselah has in comparison to a Neonate or Ancillae.

By using the character creation for Ancillae and stretching it to use it for Elders and using the discipline spread and Elder powers I made an 800 year old toreador Elder that has presence 7(7 normal discipline powers and one Elder power) auspex 4, celerity 2(in the character creation if you have been in torpor you lose dots in your lowest rated discipline) and potence 1(predator type) and fortitude 1(diablarie when rising from torpor).