I thought of a neat little exercise in order to improve my orchestral emulation skills. I took the score and audio of Beethoven's 5th Symphony and tried to emulate it using virtual instruments. Here are the results (only the first part of the 1st movement):
Beethoven: listen online
I'd recommend anyone wanting to be able to realistically emulate an orchestra to try doing something like this. I definitely learned some new things, not just about virtual orchestras, but also about orchestration.