I play a piece enough times where it is all automatic, as far as what note comes next. then I am free to think about volume, speed, articulation. If you don't have the Busoni transcriptions, look at them, he works out exactly which notes "should" be separated and which ones should be legato together. It comes out very standardized since he lived in 1860, but I love the sound of his markings. I never hear anybody on the radio doing Busoni markings, either.
The piano gives one the ability to mess with volume on individual notes. I like to accent odd ones, which is a jazz type of practice, but which probably would drive a baroque purist that played harsichord to a frenzy of criticism. I do inventions 2,4,8,11,13, 14, and occassionally when I feel sad, 9.