We typically don't have the luxury anymore to replay games since most of us lack the time due to jobs, family life, too many other games, etc, but would there be a game you would really like to go through again?
I used to play through the first MGS game once a year since its release for like 5 or 6 years and I have replayed many adventure games like Full Throttle and the first two Broken Sword games. But the most recent one I can think of is the first two Gears of War games... oh and actually Half Life 2. For GoW, they are really nice short, tight, single player experiences and the cover and shoot mechanics are still the best that's been done while still being the first. While I was really miffed about the ending of HL2, I still found its world and passive environment story telling narrative to be amazing enough to come back to.
What are your picks?