Ok, after one beats the main quest, is one supposed to just run around and do other ones? What if....one has beaten all the quests they can possibly find? Is there some other big important thing to do, or does the character just get old and die, or do you just raid caves forever? If...someone could help me out, that would be cool. All the guild/group quests: check. Arena: check. Main quest: check. Wandering around looking for inns and towns: check. What else is there?!
Well once all quests are completed I think the game is designed for you to simply stop playing that character and start a new one. Try one pure evil, or one pure good, only joining the evil/good factions. Should be an interesting change instead of running around doing 'nothing'. See how you get along if you have 100 infamy points and 0 fame points and everyone's attacking you... (if that is possible).
Anyway I envy you for wanting to play the game for so long. I got fed up even before I did all the quests. Hope I'll get the urge to play again soon though.