The game rules are expansive enough for the character to play as an avatar and there's a lot of room at the top for high powered gaming.
When i finished BG2, I felt that there could be more done with the following:
1) Getting Aerie's wings back. Why can't she get them regenerated? The in game stated reason (her muscles have atrophied) makes no sense. If there was regenerative magic, then priests would either learn or have others trained in physio.
What about if it was part of a sinister plot to take someone who would have been a champion for her race, and one day led them to victory against the evild dragon hordes, and condemn them to wander in darkness and despair until they could be twisted into the service of evil? What if the main character had changed that outcome? Tiamat would not be pleased!
2) Saving Viconia. Fight your way to the abyss through the unnatural and twisted denizens. A nasty, chaotic environment (anyone here remember the Q1 (and Q2?) modules?). Take out Lolth. For good. come back with Viccie and her brother for good measure. They are held against the laws of the planes as they are not evil ... well, i think Viccie isn't, just *damaged* by an incredibly abusive (in every sense) upbringing, and having her brother save her only to be corrupted into something foul by Lolth is enough to make anyone bitter.