Another millennial here. Your S Class interior image looks great to me. I'd go black over brown but still looks great. I just looked at some pictures of the Tesla and my god that looks awful inside. The inside of a luxury car should be a lot nicer than that. Also why the giant screen? Knobs and buttons make so much more sense - they're easier to use without looking while driving. I've also heard various stories about people rebooting their cars essentially because everything is baked into that screen. It just seems like a downside to me in every way.
You picked like the most old-fashioned style you could.
http://automiddleeast.com/wp-content/uploads/2015/01/AMG-spo...
I'm 25 and I would pick this over plastic and poor leather in tesla any day.
Go sit in both, they're not even close. I'm a millennial too, but that has nothing to do with being able to appreciate a luxury car interior. FWIW neither the S Class or Model S appeal to me because I like going to the mountains and drive on sketchy forest roads.
http://www.arodmercedesbenz.com/wp-content/uploads/2015/04/S...
But I say this as a millennial with an engineering degree, so I don't really know if the marketers particularly care about my opinion on what is stylish or not.