For years I had a Window profile; this was because the Client I travelled with most is a small guy and liked window seats. We were often booked together and this guaranteed a window for him. I personally prefer aisle seats. He has now retired and I have gone back to my aisle.

I am 6' and 95kg and can just sit comfortably in a standard Y seats as long as there is no COS beside me. In a aisle, at least I have another 6 inches of space, even if sometime I take a whole flight leaning to one side.

Anyway, two incidents spring to mind, both in Y:

• I had been allocated aisle 3rd row in Y on a 767 (25J). On boarding I found it occupied by a young woman. When questioned she pointed to the vacant 25F across the aisle saying it was her's and would I mind taking that seat. No harm being done, I sat there. Shortly afterwards, another woman comes down the aisle flashing her BP for 25F. I refer across the aisle to the occupier of my allocated seat and she pulls out a BP for 23J. The second woman is ok with this and proceeded forward to this seat. After a few awkward moments, everything is fine.
  
  Why this game of musical seats? Well, row 23 is the front of economy and is a bulkhead seat. The first woman wanted her handbag with her and knew that in a bulkhead seat it would have needed to be placed in the overhead lockers.
  
  Why did she go about it the way she did? Why did she lie about her seat? I would have happily taken the 23J. I'm not really sure, but she was a pretty young thing and is probably used to getting her own way and was not used to being queried.
  
• On a full 737 I arrived at my Y class aisle seat to find a guy sitting there. On showing my BP to him he said straight out "I always have an aisle seat", no ask, no politeness. Surprised at this I stated "So do I and you are in it!". Giving me filthy looks he arose and proceeded two or three rows back to his middle seat.
  
  I guess he was simply trying to bluff his way into more comfort on a two hour flight. As to his methods, they leave a lot to be desired.

I guess if a request is like seat for like or better I can normally accomodate it.