Thread revival!
I haven't done much with mine on the inside. Really, I pretty much like it exactly as it is, as far as colors, materials, etc.
But, one thing I had to change was the steering wheel. I don't know what leather BMW uses for the non-M sport wheels, but it feels and looks like polyurethane. I rewrapped mine with Nappa leather.
A much needed improvement, feels significantly better in the hand.