I've got the sat-nav, and it's not much good. At least if you order now you'll get the Traffic Message Channel (TMC) which is standard even on Ford's now but something Porsche 'left-out' of our 997's and wants to charge £450 plus VAT to put back in from August ! TMC is supposed to navigate you intelligently to your destination on the basis of live traffic information. That is the subject of another forum !
My 997S I adore, I have the phone, Adaptive sports seats (not sure they are really any better than the basic ones) parking sensors, cruise which I find very useful to avoid speeding on the M40, heated seats are good but the car warms-up fast anyway, the phone is awful (again another topic), Xenons are great, PASM is great, 19's are fine with the PASM. Got the BOSE, which has a vast range of settings which appear to make no appreciable difference at all, regardless of the type of music or volume ! Got the CD changer too, which is no longer necessary since the navigation uses a DVD drive in the luggage compartment.
DON'T get the rear wiper - it doesn't have a wash function so smears everything and I never use it.
Tyre pressure warning was knocked-off my order as not available on the early 997's, but may be an asset.
Colour, I can't believe no one has told you about SPEED YELLOW ! I wanted it but had to settle on Basalt again after pressure from the Mrs, but Yellow looks amazing on these. I went to the 997 forum meet at PCGB Reading, and one guy (apologies I forget his name) had a 997S in Yellow that everyone loved ! You must try to see it to believe it ! Also, another member had the sun-roof and said it hummed really badly when open on the motorway...
Good luck and enjoy it - you'll be happy whatever you choose !