Not something i normally think about, since it almost never comes up, even in games with planar adventures. Unless the connections are relevant for an adventure, the information needed about the planes is fairly limited (mechanical changes, description, denizens, etc.).
That said, the Great Wheel (which is really a rectangle from 1E) is my default. I like the idea of switching things up for specific campaigns though, as universe building is a hobby of mine. My current idea I've floated around is that there are only three planes of existence: the Heavens (home of the gods, celestials, and redeemed souls), the Mortal Realm (material plane), and the Underworld (basically Hell, but with the Abyss underneath it). Mortals who die go to the underworld to be tortured by devils (under the rule of the god of the underworld) until the god of Justice feels they have suffered enough for their sins and are taken to Heaven. Souls driven insane by the devils are tossed into the Abyss to be torn apart by demons (who are the remnants of the nothing that existed before the All-Father brought the universe into being)
That said, the Great Wheel (which is really a rectangle from 1E) is my default. I like the idea of switching things up for specific campaigns though, as universe building is a hobby of mine. My current idea I've floated around is that there are only three planes of existence: the Heavens (home of the gods, celestials, and redeemed souls), the Mortal Realm (material plane), and the Underworld (basically Hell, but with the Abyss underneath it). Mortals who die go to the underworld to be tortured by devils (under the rule of the god of the underworld) until the god of Justice feels they have suffered enough for their sins and are taken to Heaven. Souls driven insane by the devils are tossed into the Abyss to be torn apart by demons (who are the remnants of the nothing that existed before the All-Father brought the universe into being)