Cant speak for the US, but in general, Covid is still more dangerous during the acute infection than the flu and also causes much larger numbers of post-viral sequelae. Those are all potential reasons to recommend the vaccine, which can reduce the severity of both

I like lighthearted ones such as the Barber of Seville or “Zar und Zimmermann”. If you want more oomph, The flying Dutchman is a great choice. I also like Carmen and Nabucco for some really catchy melodies and the magic flute is nice too. Depending on what language(s) you speak, some of those will obviously not be foreign, sorry :-D