Hm, there are many good games which I liked to play gain, but only after some time. If I play trough a game, I always want to discover all what is possible to find - so, I rarely encounter somethig new
. Especially old SNES games like Final Fantasy VI, the Dragon Quest series and Bahamut Lagoon are amazing enough to replay them.
On PSX, I really enjoyed Grandia I; Front Mission 3 is also nice, but I haven't played it trough yet
.
On PC, the only game I played and where I can say it is worth at least one replay, is Baldurs Gate II (never played part I, sadly). There are some other very excellent games like Half Life 1&2, or Deus Ex, but those don't offer much new you can discover in a "second run"...