I'm thinking ahead to festive afternoons with bigger groups of family/friends around over the holidays, when people who know that I am a coffee enthusiast often want to taste what I can make. With that in mind, I'm trying to think through what espresso(s) might be best/most serviceable for such occasions. A good option for this purpose always needs to be something that (a) is interesting and good enough to show people what excellent coffee tastes like compared to what they think is excellent at $tarbucks, (b) is not idiosyncratic but has broad enough appeal in its flavor profile for the non-specialist, and (c) tastes good both as straight espresso and in shorter milks drinks (5-6 oz. total) to accommodate people who go either way.

Any recommendations/preferences out there for such purposes?

Metropolis Redline, reviewed here, would be high on my list. More old-school sweet flavors than many recent blends, works well with milk, and seemed to me to be very forgiving of extraction parameters, especially compared to many of the other SOs and blends I've been using. A cup that I'd be very happy with if poured, yet without the bright acidity common in current offerings.