I thought the Desert Palace had some particularly nice bits to it so I suppose for my own personal mansion that'd be the place I'd have. Sadly, given that it's in the middle of no where and the only places I could have non Black Mage contact are Conde Petie (*shudders*) or Madain Sari (*slightly more severe shudder*), I think I'd have to opt for either Lindblum or Burmecia. I think Lindblum has the right amount of eccentric for me.