What is the 6K service for? Oil? Why not do it yourself, save money and time. If that's not an option though, while going from Bonneville to Death Valley, it might be worth it to stop in Vegas or Reno depending on your route for the service, Long Beach BMW is really expensive.
And are you planning on staying in San Francisco, or going back to NJ? If going back to NJ you might want to up your mileage estimate a bit. Going straight through on the freeway is about 3K one way, add in detours and fun roads and it'll be more.
Not trying to discourage or anything of the sort, just trying to help out.