If you want to hear how a system performs, really get a measure of what it's capable of, then you probably should select some music that shows off its best qualities.
I certainly have my baker's dozen I whip out to impress first-time listeners to the system: sure winners with great soundstage, proper tonality, and often impressive low end.
But then the real test comes in. For most experienced listeners, playing their favorite track of music on a new system is the key to getting its measure. That's why at tradeshows so many audiophiles go from room to room hoping their discs will be played by the manufacturers. Many will not. From the manufacturer's viewpoint, they are there to show off their system's prowess to as many people as possible. Putting on someone's unknown music has the potential of pleasing one at the risk of alienating many.
The way we handled these situations was to ask the person to wait for a brief lull in the crowds before we played their track. Sometimes we were rewarded with discovering great new music, but always, our visitors were rewarded with hearing a track they were familiar with.
It's great to have your sonic spectaculars at the ready—and you should—but it's also helpful for guests to hear what their favorites sound like on a new system.
In this way, we both benefit.
