Disregarding aviaries that limit mixing to raptors (e.g. 2 eagle species together), the only mixes that I'm reasonably sure have been a success long-term involve secretary and bateleur. For example, at Walsrode, Germany, secretary has been kept for many years (I believe 10+ years) in their big 0.3 hectare/0.75 acre aviary with various storks, ibises, ducks, etc. I've seen bateleurs in a similar and apparently successful setting, but can't quite remember where? However, both these species rarely, if ever, take healthy, adult large birds in the wild and I guess this make them less problematic than most eagles.
From what I can understand, the problem with most eagles and hawks is that, even if they don't typically prey on the species they're mixed with, they can be rather hostile towards them. Regardless of possible inter-species aggression, I personally wouldn't call any exhibit based on raptors with clipped wings a success, but that has been discussed before on zoochat.
Vultures arguably belong in a separate category and are mixed much more widely. Commonly only a few vulture species mixed together, but sometimes also with large corvids, storks, ground hornbills, caracaras, etc. At the huge 1 hectare/2.5 acre South American aviary at Doué la Fontaine, France, Andean condor and turkey vulture are kept with a wide range of other medium to large birds, mostly parrots and water birds.
