I would strongly recommend heated seats. My last 530d had no heated seats and they were cold!
also helps resale. I would not buy a car with leather which did not have heated seats. I use mine in current car all time. You can add them after but it's £500.
I agree about the business speaker upgrade, money well spent if you like music.
Not sure whether you have added Bluetooth either but I think this will become a must have on resale.
In my opinion if you want to save money consider dropping the electric seats. Although quite cool and easier to get adjusted than manual. Once the seat is set that's it. Of course unless you have more than 1 drivers where they make far more sense.
Just my two cents
Bear in mind any changes may delay delivery, it shouldn't but that may have happened to me, or it could be they told porkies when I ordered saying I would get it in April which is now moved to end June