Thing is, most of the locations in the Capital Wasteland were pretty much totally insigificant and were just bloat. Many of NV's locations actually have some meat to them.
More or less this. Although I ABHOR the fact that this iteration contained a few very obvious invisible walls (used largely on rock faces I burned to climb for a better view), I took comfort in the fact that 90% of the locations I ran across had some sort of significance in the grand scheme of things, whereas in FO3, most of the locations were just little dungeon dives that yielded, at best, random rewards, with the odd gem (like the BoS Med-X armor underneath Old Olney.) In my opinion, the Mojave feels far more alive than DC with designated habitats for certain beasts, varying scenery (EVEN SNOW! WHAT!?) and lots of random encounters with various denizens of the wasteland.
In DC, there were a lot of buildings and caves and holes, but very few people encounters out in the wastes. Sure, you'd run across the odd hunter, mercenary or wasteland doctor, but it was never an interesting, unique experience like most of what I've found in Vegas.
Most of my time playing Fallout 3 i was simply exploring the "dungeons", sure it's bloat, but pretty delicious bloat
So are there really no such non-quest related "dungeons" in New Vegas at all? (won't get to play the game until next week.)
Yes. There are still lots of little dungeons to poke your nose around in Vegas. I'm not sure if there are as many, but there are still enough to lose yourself for hours and hours in them. As a bonus, a lot of them have hidden story goodies, like one dungeon where a veritable LEGION of lakelurks capture and kill a squad of NCR troops, and you find the one survivor and clear the cave while helping him escape. It's not even a quest, but it's very fulfilling,