I have a desk set that works really well for me now.  When we went to design my built-in office furniture, I used the same dimensions.  However, looking at the desk one day, I noticed that the space for my chair under the part that I was likely to be using the most, was too small.

The overall side of that part of the desk is the same as my current desk, so I was a little puzzled on how this happened.  As it turns out, the return on the left side was just a few inches wider, and the drawer set on the right is just a few inches wider than my current one.  the overall results is a loss of about 6-7 inches of chair space.

The solution was to remove and alter the drawer set, like this:

As you can see, such a change isn’t without implications for the flooring, which will have to be patched properly, at a cost.  But at least now I will have enough chair room.  The built-in desk has a plethora of drawers on the wall part behind the desk, so the loss of a bit of drawer space there isn’t too bad.