John,
Wait, you actually play music with your wife?! Woah. Mine just mostly yells at me. Hehehe.
Anyways, what I'm trying to avoid is the long wait time while I render the piano track, when I don't even need it. When I play duo gigs with piano and sax, I mute the piano track the whole night... it would be nice to not have to wait for it to render. A nice preference setting would be "do not render muted tracks."