Let It Be, Yesterday and Hey Jude are compulsory, for sure. Band On The Run is probably, too, as it's something that the casual Macca fan might be familiar with.
Remember, Paul has two extreme groups to please.
1. People like us who are devout fans and know all his albums inside out. We want to hear our favourites, many of which may be obscure ones. So he will play the odd lesser-known song here and there.
2. People who know Paul as a Beatle but are clueless about his solo work. He needs to play they identifying songs like those listed above, and also play the ones with the best chance of these people "getting" them.
So he compromises. It's that simple.