For a younger feminine spanker, I'd like her wearing a cheerleader's uniform, especially that of a 1970s-style Los Angeles Rams cheerleader.
For a thirtyish or middle-aged woman spanking me, I'd prefer her attired in a classic blue police officer's uniform.
Still, of course, I'd never refuse a bare-bottom-up trip across the lap of a female Starfleet counselor...

--C.K.