Oh, but did you know they added a corridor after the season 3 retooling of the mansion set, i.e. moving of the staircase? Suddenly it's L-shaped. In other words, when you arrive upstairs the master bedroom and most of the other bedrooms are still to the left, but instead of the corner guest room to the right where Claudia had stayed in S2, there is now a whole new corridor (apparently Amanda's room is down that one in S6).
Surprisingly, that does make sense, because that's above that left wing of Filoli (where the kitchen and the accompanying servants' quarters were). I'm not sure if we ever actually see that corridor, or we only see people entering and exiting it. Of course, it only makes sense if it's a very short corridor, because the second floor doesn't actually cover the entire left wing.