I have Mineral Grey and, whilst a lovely colour, it's not worth the cost if you're limited on options.
The folding seats do give plenty of storage scope for a saloon. If you like your music, and listen to your own rather than the radio then HK is a must. Equally, if you do just go with radio, then DAB is worth it.
I have the Pro Nav so can't really advise on single options which are included within it, but if you do have to make/receive a lot of calls then the enhanced phone functions would seem sensible. Not sure if that would include SMS/email functions, but if it does it's very useful to have them read to you by the car while driving.
I wouldn't bother with 19" wheels, certainly not going to offer anything ride-wise and will dent your option funds (not to mention tyre costs later!).
As for beige interior in a white car - are you auditioning for TOWIE or something?????!