I've always wondered if Alexander's Theme was played on a real grand piano by Mikko Tarmia or not. The first few notes are so crisp and resonant I don't know if they could have come from an electronic device.
Instrument libraries are pretty advanced these days.
I always felt that the song sounded a bit harsh in terms of dynamics. All of the notes seem to be of a similar intensity. That's either a library limitation, lazy programming, or intentional.