With regards to the best table, in my experience the restaurants actually did keep the best tables for us despite having busy days.

Amuse bouches and desserts were offered to all guests at the table - these were nice complements. In some instances the extra desserts were not plated individually but served in small vases and placed in the middle of the table.

Farewell gifts were quite symbolic and nothing exceptional - a box of chocolates, a cook book, etc. They were presented individually to each guest in case that matters.

What I appreciate is the discretion of these benefits most of the time. Restaurants would not announce them loudly but you would notice the Centurion benefits throughout the dinner and on your bill (at $0.00 of course), therefore your guests would just be enjoying an enhanced experience without knowing why it is happening.