This thread made me curious, so I went ahead and looked at all the Unique Infrastructure to see which yields are represented the most.
6 Faith (tlachtli, sphinx, stepwell, stave church, kurgan, mission)
Faith is represented a lot, which isn't really surprising. Almost every civilization in all of history has had its own unique religious structures, so they're an easy source to mine when coming up with ideas for unique buildings or improvements.
5 Gold (great wall, royal navy dockyard, chateau, mbanza, kurgan)
I was not expecting gold to be the second most common yield. The rationale behind some of these seem a bit odd. Why does a gravestone produce money? Probably shouldn't thank too hard about that.
4 Culture (great wall, sphinx, chateau, acropolis)
Culture is also well represented, though not as much as you might think. Notably, every culture-producing Unique Infrastructure except the chateau were wonders in previous Civilization games.
3 Great Person Points (tlachtli, street carnival, royal navy dockyard)
This is sort of cheating, since they all produce different kinds of great people, but I don't want to make this list any longer than it already is.
2 Amenities (tlachtli, street carnival)
2 Tourism (film studio, great wall)
2 Production (hanse, electronics factory)
2 Food (stepwell, mbanza)
2 Housing (stepwell, mbanza)
Most yields are only represented by 2 Unique Infrastructures. So far, anyway.
1 Defence (great wall)
1 Promotions (royal navy dockyard)
1 Science (mission)
Military specific bonuses and science are only represented on one Unique Infrastructure each. Is this because structures dedicated to learning and education tended to be pretty homogenous, even among civilizations with radically different cultures? It gives you something to think about, at least.