JFK-LHR and LAX-SYD would be obvious choices for me. However, since most DL hubs aren't prestigious (like ORD, LAX, JFK, maybe BOS and LAX), the number of prestigious segments or city pairs is limited. For PMNW, MSP/DTW-NRT would have been relatively prestigious, as would the HKG nonstops, plus MSP/DTW-AMSa d BOS-CDG when it operated. I want to add some nonstop to South Korea to the list, maybe ATL-ICN, since routes to big Asian business cities tend to be prestigious, however it's defined.

Among domestic flights, surely JFK-LAX and JFK-SFO (all nonstops with D1 service) would be prestigious.

With the postCOVID-19 shift to leisure travel, I'm tempted to add ATL-HNL and MSP-HNL or generally any D1 route to Hawaii.

Add the old PanAm JFK-NCE nonstop to the list, even though it's seasonal.