I'm disappointed at the dungeon aspect in FO:NV as well.
For pure copy/paste, nothing was worse then Oblivion. The old ruins were way too overused and the design was very blah. FO3 did a much better job of it. No two locations were exactly the same (other then house layouts). The metros were slightly repetitive, but it's a modern society and that's how things are done in modern society. But the radio cisterns were all unique layouts as were most of the larger indoor buildings.
When I ran across Nipton's town hall, I was very impressed. Here was an indoor location that was more then 3 rooms and a bathroom. The ruined REPCONN factory was wonderful (if maze-like) as was the Bison Hotel. But the Boulder City Ruins - were an absolute joke where you could see the entirety of the area from the entrance (nowhere near as good as Germantown Police HQ). The design of the Hoover Dam is good/bad - big, but also hollow in a lot of ways on first glance.
I foresee lots and lots of cells being added by modders (CevSteel has already started a NVInteriors project).
Oblivion was horrible that way yeah, you basically had 2/3 dungeon models: Forts, Ayleid ruins and just...well..CAVES. Still, the atmosphere and the way some of the places were done made them acceptable. FO3 was WAAAAY better in that regard, I particulary enjoyed the Dunwich building (which is a reference to The Dunwich Horror, a, you guessed it, horror novel and the Old Ones from the Cthulhu Mythos) because it was scary as HELL, with all the illusions, and a slight hint that there was something evil watching you all the time. The reward of the place wasn't anything special, but the story of the place which was laid out through computer entries by the former pre-war employees and the aforementioned illusions were just so awesome.
Also I will be monitoring that mod you were talking about, sounds great!