I'd do the same thing + B&O. Given the changes for 2013, it would pretty much be the same features as I have plus shadowline, soft-close, ventilated seats, and sun shade. The last three are part of the Executive Package, which is a must since it includes the Nappa Dash, contrast stitching, ceramic controls, HUD, and soft-close. I can't see too many of these being built without this package.
Because I'm a masochist I had to build my car on the BYO site, and it came out about $1500 more than my MSRP but included soft-close, shadowline, vent. seats, and, obviously, the engine upgrade to 450 hp.
The B&O is the only thing I really wish I would have added, and, in hindsight, I'd add the Driver Assistance Package for the top-view cameras (the only component of that package I've ever really desired due to poor visibility).
So, to answer your question, my 2013 build would be:
Comparable Build:
M Sport w/ 20" 373M Wheels
Lighting Package (Full LEDs)
Executive Package
Cold Weather Package
Adaptive Drive
*B&O (skipped this, and the regret is killing me
)
Ideal Build:
Same as above plus...
Citrin Black Individual Paint
Opal/Black Merino Leather Interior
Piano Black Trim
Driver Assistance Package
At this point I'd just have to throw an extra $15k into it and supersize it to an M6