While I'm not crazy about the poles and mesh covering, it is certainly interesting to see bongos in a mixed exhibit, especially with monkeys. I don't know of any other bongo mixed exhibits (there may be some, I just haven't heard of them).
Woburn Safari Park has kept Bongos with a variety of monkeys since re-opening their Monkey jungle - currently Patas Monkeys and Barbary Macaques (with Drills soon to be added).
Jacksonville zoo's bongo are kept with an impala, stanley crane and s ground hornbill. NC zoo will soon have bongo with giraffe, zebra and ostrich. Metro Richmond zoo's bongo are kept with giraffe, gazelle, greater kudu, crown crane and white stork. A while back a single bongo was kept with the three african elephants at Roger Williams park zoo. Its cool they are kept with primates though. I have always wanted to see bongo or okapi with pygmy hippo and another central African primate (or two).
Okapi and Bongo I doubt will ever happen, although I'm sure Okapikpr could have a lot more insight on this. As for pygmy hippos, I personally would love to see them with bongo. There is no reason that this exhibit at Caldwell couldn't have pygmy hippos as well without doing a lot of renovation.
Bongos and primates, and a bongo with elephants-very interesting mixes. Thanks for mentioning them.
About the other combinations mentioned: I would be careful about mixing kudus and bongos due to possible hybridisation.
Prague Zoo temporarily keeps (kept?) their bongos in a wild mixed of African hoofstock and secretary birds (see Gallery). I have seen various zoos keeping them with duikers, too-although there have been some occasions with the duikers being hostile and aggressive torwards the bongos.
About pygmy hippos and bongos: I think the Mountain View Center kept them this combination once. However, I would be careful with pygmy hippos and antelopes-I read a report about some pygmy hippos attacking and injuring sitatungas in the same exhibit. Let's see whether the Valencia combination will work or not...
Okapi and Bongo I doubt will ever happen, although I'm sure Okapikpr could have a lot more insight on this. As for pygmy hippos, I personally would love to see them with bongo. There is no reason that this exhibit at Caldwell couldn't have pygmy hippos as well without doing a lot of renovation.
Someone correct me if I am wrong, but aren't DAK's bongo and okapi together? If not, I know there is a big mix species exhibit with okapi in the works at DAK's the Lodge.
@ Sun Wukong- Unfortunately, I don't think Richmond Zoo is worried is worried about hybridization between bongo and kudu. I wondered about that when I visited last summer.