That actually sounds good. It wouldn't be that much of a drain on the budget too (unless I'm wrong about that).
I also realize that someone said earlier that not everyone will play everything. I agree to an extent; when I played through BG2 I never went Druid or Monk, so I never got to see their fortress/stronghold content.
Yeah. It would be cool if you get a class benefit at the end, or something for the stronghold even. Like a permanent boost to your animal companion if you're a ranger, or an additional weapon spec. for a fighter. All that cool jazz.
Will there be any unique class quests? The idea is similar to Baldur's Gate 2 wherein the class would be assigned his own quest chain. The Cleric, for instance, would get a quest which would help their deity, the Chanter would have to make a song that would echo for eternity, etc.
I think it would be a great fit for this flavor of CRPG.