I am not a great pianist, but I dabble in it, and am good enough to play pop. I also have friends who are GREAT pianists.
I use a touch sensitive keyboard and play parts myself that record basic velocity, articulation and such. I then run it through either Garritan's awesome Abbey Road Grand(s) which has many controls for top down, top up etc. or just a regular GPO 5 piano if the part is way in the background.
Honestly, I think the piano sounds that come out in the end are lovely, and I am flabbergasted by the quality of modern technology. Some stuff played back through good samples using midi tracks which were recorded by great players sometimes sound as good to me or better than a mic'ed piano in a studio.