Locations described in the 3E Manual of the Planes p 101-103 (some listed above, repeating here since that's how I typed it)
Plain of Infinite Portals (also Broken Reach and Ferrug)
Azzagrat (also Zelatar)
Thanatos (also Naratyr)
Layers: Realm of a Million Eyes, Ice Wastes, Demonweb Pits, Smargard, Abysm, Slime Pits, Fortress of Indifference, Noisome Vale
Book of Vile Darkness briefly described the realms of the five major demon princes: Demogorgon (p125, his palace Abysm and his fortress Ungorth Reddik),
Graz'zt (p 131, capital city Zelatar and his Argent Palace),
Juiblex (p 134, no real details on the Slime Pits),
Orcus (p 137, fortress-city Naratyr mentioned),
Yeenoghu (p141, his layer mentioned as well as the layer controlled by his vassal, King of the Ghouls)
1E Manual of the Planes (p101-103):
mention is made here that the inhabitants of Gladsheim (Ysgard now) call the Abyss "Demonholme" and those of Arvandor (the elven realm on Arborea) call the Abyss "Jurgarten" (misshapen lands).
The first plane of the Abyss is given a few different names: Pazunia (because he is commonly found there), the Plains of Infinite Portals, and the Palace of 1,000 Closets, and is described therein.
The realms of each demon lord existing at the time (Orcus, Demogorgon, Yeenoghu, Juiblex, Lolth, Baphomet, Fraz-Urb'luu, Graz'zt, Kostchtchie, Pazuzu, and Zuggtmoy) are discussed briefly. Some notations (though things have been clarified, expanded, or changed over time):
"The Realm of Demogorgon spans several layers..." well, obviously the 88th layer (Gaping Maw, Brine Flats) is his main home. Rip mentions above his Jungle Realm from H4 Throne of Bloodstone (though this could just be an older description for the same plane), and Demonwing the wandering layer from A Paladin in Hell. Undoubtedly, "several" leaves room for a few more bases...
Kostchtchie does not dominate his whole layer, but his hatred "spans the layers of the Abyss".
"Zuggtmoy has several realms scattered among a number of layers..." though presumably this came to an end while she was imprisoned, and was stuck sharing a layer with Juiblex? Of course, what once was can always be again...
even briefer mention is made of some gods on the Abyss, such as Vaprak, Laogzed, and Urdlen. Feng-Tu, the realm of Tou Mu and Lu Yueh is described, as well as the layer of Kali.