If you can live with looking a cheapskate with a tom tom in a 40 K motor , then the tom tom is the way to go.[

]. Try sports seats before ticking the box as unless they are the full adaptive (electric seat option) some find the shoulder supports too constrained and actually more uncomfortable than standard on a long journey. Park sensors are a "nice to have" particularly if you live in town or park on the street. Anything that isnt porsche fitted originally or as a dealer option will invalidate the warranty so check on the CD head unit regarding connectivity to i pod and USB. I know the PCM has USB connectivity and can have bluetooth added as an aftermarket fit by the dealer without the need for the full phone module. Heated seats and a wind deflector are a must particularly if you plan to drive with the roof down in the Uk with less than ideal sunny weather. The soundpack is just an upgrade of the speakers and addition of an amp, i dont think you get any extra connectivity.
I can only speak for my personal experience , I have an S model with PASM, PCM, Sport Chrono Plus, PSE exhaust, Tel module, Dension USB/Ipod adapter, Multi function wheel, Techart padded steering wheel, 19" wheels , 5mm wheel spacers, Full electric memory seats, Bose sound upgrade, Xenon headlights, Climate upgrade, wind deflector and full leather trim with heated seats and short shift gearlever.
Of the options fitted currently , the only ones I'd spec from new would be PSE, short shift, padded wheel and a sound upgrade rather than Bose, with a USB interface and wind deflector. All the other add ons are expense you can live without and dont really increase your enjoyment of the car. The 2.9 is very close in performance to the 3.2S I have currently so i'd have no issues with a 2.9L engine. Having driven with other boxster owners I can vouch a well driven 2.5 986 is capable of keeping up with a 987 3.2 S in virtually all situations. Under normal driving conditions you wont notice the difference in brakes between the S and standard. I also prefer the black instrument dials of the standard to the silver of the S. As to colour , personally I like the solid colours of White or Red in the new model , though paint to sample is only marginally more than metallic I believe. If you want to make a statement on individuality without loading the car with options , the exterior colour is one way to do it, or have the car vinyl wrapped which protects the paint underneath whilst giving a unique colour or finish , black works well as a base colour for a wrapped car as the edges dont look awkward where the wrap ends.