For the most part I don't replay any games, whether or not I loved it. I just recently decided to do MW2 on veteran and it was worthwhile but I haven't played the campaign since release so I had forgot everything. The "raining helicopters" as great, all the vehicle parts were awesome - I totally forgot about how the game ended with the whole driving a jeep into a moving plane, driving the Kodiak boat, and of course the very end with Shepard(sp?). I tried starting BioShock 2 over on easy after beating on hard to do some of the trophies (no deaths, perfect little sister defence) but I just can't do it yet. Too soon. Maybe in a couple months I'll go back. A game I think I'd like to beat again is Half Life 2 since I absolutely loved it, but I've not played it since beating however many years ago that was.
Also I just beat Heavy Rain last weekend and I'd sorta like to do it again to do things different, but again, just too soon I prefer to forget a lot of it before trying again.