Having fully explored every location in Fallout 3, I was wondering how many locations are in New Vegas and how do they compare to the ones in Fallout 3. I did not really enjoy exploring them in FO3 because they were all basically the same and most of the time did not have an associated quest or any special items to be found within them. However, I did fully explore every one of them because I am that sort of completionist/OCD person. Thanks.

I think there are 215 locations

I personally think it's worth exploring, but there are quite a few locations that could be considered redundant. The explorer perk might interest you, if only because you can see which are "abandoned" such and such and then decide which ones you want to check out.
But for me, exploring blind is just as much (if not more) fun than the quests themselves

Loads and loads, I haven't found everywhere yet and am on my 3rd character with over 120 hours on just that character. Where is the emoticon with bloodshot eyes with bags underneath? Some of the locations aren't that exciting, but I was up to 100 hours before I found all of the NCR bases that had quests.

There are 187 primary location.

However "explorer perk" only shows 186.

Anyone knows where the last location is?

There are several locations that aren't given a map marker, but you get the same "dun dun duuuuuun" sound + an area name, when reaching it.