It depends.
Some games I've played and then replayed multiple times because they're just that enjoyable.
Games like Chrono Trigger and some of the Final Fantasy games have great stories and characters that, like re-watching a movie, or re-reading a book, I want to experience them again. Or games like Mega Man X, which is so well-polished and so fun to play that the linearity of the experience doesn't take away from the fun factor. Or games like Super Metroid, Metroid Prime, and Bioshock, where the atmosphere is so rich and engrossing that the feel of just BEING in the worlds of those games is worth a second, third, or more trips back.
Some games have variations on subsequent playthroughs that practically demand multiple playthroughs if you want to experience everything that the game has to offer: Dragon Age Origins, inFamous, and a lot of different RPGs offer this.
Some games have such emergent gameplay that you're never going to get quite the same experience each time: games like Civilization, especially when you change difficulty levels, offer drastically different experiences on each playthough that if you enjoy it, it feels natural to play it again and again.
But there are some games that I enjoy for the time and then never really want to touch again. I recently sold my copies of the Uncharted games because I never saw myself playing them again. I certainly enjoyed them as a I played them, and I'm glad that I did, but I couldn't see myself going through them again, it was more of a one-time experience sort of thing.