My father is similar in tastes to whoever you are buying this car for. He has a Pan TT and a S63 and to keep the long story short he drives the S63 more because it is more comfortable and usable for everyday driving. As much as you don't want to hear it, the S may very well be the BEST choice for your family member as well but if you wanted to try somethign new I can see how a flying spur would be a great choice. Honestly, we tried to convince my father to get a Bentley CGT or a flying spur when he was shopping around but he didn't want to attract a lot of attention.
Oh and there is always the 7..
Peanut Butter Chunky