mine was "RSPECT" for my K12R. remember the K12R ad campaign? it was "RESPECT". i actually like that the plate isn't fully spelled out. that way the first "R" represents the "R" in K12R. in your case, the "RS" would work too. "RSpect". i dunno. just a thought.
i personally think spending the money for vanity plates only to show the brand or the model is lame and unoriginal. how many ways do you really need to advertise you're riding a bmw? let's put it this way, if you saw a Harley with "H-D" on the plate, would that impress you? we all love our BMs, but it just screams "i am compensating!" when you have to reiterate your brand.
your vanity plates ought to make the person behind you think "ahh, that's clever!"
a friend who also rides a K12R got plates that say "FNFAST".
lots of possibilities...
"L84WRK" - Late for work - explains the speeding
"U R M" - Ultimate Riding Machine
"DONOR" - OK, maybe not.
"RIDHRD" - Ride Hard
"LIV2RD" - Live to Ride
"ZZZ" - sleeper
"SCHNLL" - can't go wrong with German.