I tend not to try and center each trilogy around one character, because to be honest, none of the characters are that complex, and no one could carry the story entierly on there own, not even Han.
I don't want to give any of the characters that much credit where it's not deserved, I always prefer thinking of Star Wars as the western set in space, and its all those strange and wonderful aliens and locations which create that truly amazing effect.
The best parts, in my opinion, of the OT were the scenes when your hero's conflicted, such as Han and 3PO, Luke and Han, Obi-Wan and Han, Leia and Han...wait, that sounds like the narrative centers around Han, which is not true, as the OT is not Han's story.