Steve,
We've just got a Cayenne Diesel, had it about 2 months - we've come from a 997.2.
Did a bit of research as you're doing, and here's some comments - probably more experienced owners around but lets kick it off:-
Facelift came in 2014/15 ish, before that boot power lift was an option.
We've got a pano roof, because we thought it would help let in and 'brighten' inside - its great.
Get a reversing camera - its a big vehicle and rear vision is not great, we've no camera and miss it, but other spec was good so... you certainly want the parking sensors.
We're on 21" wheels with PASM and air suspension. Advice I've seen and confirmed at one OPC was if on larger wheels get PASM to smooth ride, as its supposed to be harsher without on big wheels. We have no issues with harshness. We did have a loaner on steel springs, big wheels and PASM, no noticeable ride issues, but obviously didn't do a great mileage. As for the air suspension, I just fancied it as its supposed to be very good and it seems to be, whether its a must have I'll let someone else answer.
We also went for a heated w/screen - its a big car and wife did say how on earth would she de ice the screen as wouldn't be able to reach it all (I've also had to invest in one of those step plank/ladder things so I can wash the roof properly!!)
Heated seats - not sure if they're standard, most have them in the front, but think I did see one advertised without.
We also got one with a real spare wheel - I hate thinking I'll be dependent on some goo, or waiting for a 'call out' to come and sort it.
A personal 'must have' of ours was memory seats, as we both drive it and it saves endless seat adjustments trying to get that best seating position back!!
Hope this helps and happy to be corrected on the above if I've got it wrong.[
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