Regarding Austria-Hungary since I just played them, I think points for using Diplomatic Marriage on European-based City States/Independent Cities is thematic and in line with their ability. Your challenge being to survive the knife fight of central Europe while expanding your marriage network.
Possibly also having points for something like "the most cities in Central/Eastern Europe" or extra points for controlling cities in Balkans, Germany, Italy, and Poland since those were historical expansion areas.
I do also like the idea of maybe giving them extra points for Great Works of Music, due to Austria being such an important area in the history of Music.