The drow are the LEAST interesting thing about the underdark, in my estimation. Partly because you really don't need to go into the underdark to participate in Game of Thrones style political dickery or sectarian violence, so the drow don't add anything to the game that you can't more conveniently do on the surface. Partly because RA Salvatore turned them into his
magical realm, and everyone since then ran with it.
BTW, if you ever DM, I strongly recommend reading through the 4E "Underdark" supplement. Even if you hate fourth edition, the fluff it has for the underdark and its contents is batshit in all the best ways. It almost makes the underdark more like another plane of existence in how weird it is.