Many of my friends play music. So, I bring them INTO my system under the pretense of it being an introduction to simulated Quad. (using a Sansui QR 4500 for my main amp) and running four front speakers and four back with a small sub. Have a Dynaco pre (Pat 4) to help the Sansui push the speaker array.
When you sit in the sound center of the room, you can move your head just slightly in any direction and everything changes and different parts of the music recede and some peak out from different parts of the room. My system is anything BUT high-end (well, except for the Tandberg 3014 cassette I just added...) but it really does sound incredbile where I like it most, at high volume.
What is usually the theme of any demo is how loud the system is, yet really not loud like a car system with big sub, more subtle loud with depth and clarity, directional yet expansive, the Quad decoders really give me control within the mix and a great richness even at the edge of top range (about 5 on the Sansui and 5 on the Pre). I've been very methodical in putting together a vintage system that can push all my "toys" to full range. It also makes a great surround sound for movies without having to invest in a high-end 7.1 channel receiver, I have eight channels plus sub so in the end, my vintage amp wins the day.
My system is a mish-mash of brands, most of which would be considered mid'level, if that. That's the fun for me, to be able to put together a vintage system that can wow people in the room, and provides a great booth for me to do mixes in as I record a ton of cassettes and CD's and do some dubbing/mixing with multiple decks and tables.
For me, it's not about what your "victim" is used to hearing, although trying to be in the ballpark of their musical tastes can make their experience, understanding AND appreciation for what you've built, a much better time. I try to give people a number of themes, mostly rock, some jazz, and I have some great classical too.
If I'm just showing off, I play RUSH 2112 from the L.P., side one, and I can pull out my one Quad album, Rick Derringer's "R&R Hoochie Koo" which can be incredibily directional and as close as I can get to "real" quad, it's really live sounding once dialed in. Bottom line is that you ARE showing off your system, you SHOULD make the experience about your system, but first, you have to get them tuned in too, and listening! You can play them something they might know to start off, but then wow them with something that sounds really good on your system and watch their heads explode (with joy of course).
I'm enjoying this thread!