I don't really know how many hours, but I've played through 7 times, although most my games are usually shorter ~30-40 games, so my guess is probably around 250.
Around 250, including HH and OWB and 6 different characters. I wonder if I'll ever get tired of restarting the game and making always a different kind of character. I usually put most of my skill points on Guns, Repair, Survival and Melee.
Well, after 2 characters (including one which has two different endings) and one on the verge of completion, and all DLCs, can't expect much less. This game is so good.
My Yes Man playthrough now that I have all the released DLC is: 95 hours
My NCR playthrough is up to: 82 hours
My new House playthrough is up to: 12 hours
so overall: 189 hours, but I believe with my House playthrough I will reach 250 hours.
Over 1000 easy, so many mods, beta testing, tinkering, etc. Hell I put in 10 hours a day or more frequently. Half spent on Xbox 360, half spent on the pc.
Beaten the game too many times to count, and I continue to do so, because modding can change the game enough and still be fun. Like my Duke LP for instance. Or Mobucks Black Dynamite. Posing NPC's for story purposes can take a lot of time. More time than actually "playing" the game at times.
My screen reads 1111 hours but I could have sworn I played more.
It is still a good game, and with the mods that bring back restored content refreshing in some parts to play again, but when you have played it several times you know what parts will drag and where it gets good again.
I honestly would like to see some good SP mods in the vein of the official DLCs being released.
But unfortunate those are hard to make.
Lets see, on the PC I have 96 hours clocked in, but that doesn't count how much I have on my PS3 (my cpu wasn't powerful enough to play the game till like 2 years ago, so I had to play a shitty port) But literally, I think I had at least 200 hours on it.