Hi RC. I am on my second family, with two kids 16 and 10, and even though I will be 70 (gasp!) next year I am still a Porscne nut with the same expensive tastes like you. I and my family love the Cayenne Turbo S, and I drive it and all the family around daily (and on long trips). The perfect family car for a power freak like me. So I like your Cayenne Turbo powerkit choice--you will enjoy it and getting all the compliments from your family. Powerful Cayennes are superb automobiles. ( I think you should consider the Cayenne Turbo S though, as it will be nicely optioned and you will have the feeling you have the top of the line--to me somehow important).
I admit to longing for a Panamera Turbo S, but I will wait until my daughter goes to college in 2013. Then I can let the Cayenne go and indulge myself a bit more. Meantime, I adore my Cayenne...