No it's not Coruscant. Ironically, it's Tatooine! This will likely all come to fruition in Ep. III, when Tatooine becomes the only planet featured in all 6 episodes of the saga (while not appearing in ESB, it was mentioned). While in ANH, Luke basically considers his home planet to be insignificant inthe grand scheme of things, some of the most important events happen there.
1. Anakin Skywalker is found there as a slave.
2. The major turning point of his transformation occurs on Tatooine when Shmi dies.
3. Introduction of Darth Maul, the first sign that the Sith have returned.
4. Luke Skywalker, the future savior of the galaxy, is hidden there.
5. R2 and 3PO land there with the Death Star plans, thus bringing Luke to begin his journey towards destiny.
6. The deaths of Owen and Beru Lars, allowing Luke to leave the planet and join the Rebellion.
7. Han Solo and the Millenium Falcon are introduced there, two X-factors in the destruction of both Death Stars.
8. The rescue of Han Solo, tied in with Luke's maturation as a Jedi.
If I've missed anything, please feel free to add to the list and/or post comments.