In the states, there's not much for larger hornbills, sadly.
Von Der Deckens is the best represented, African grey and red billed are around and breeding in smaller numbers. The two yellow billed species are around, but are sadly becoming increasingly less common. Pipping are respresented and there should be a decent number thanks to more recent imports, but little to no breeding has occurred thus far. Trumpeters aren't common, but aren't rare either. Silver Cheeked are also around, but bred with less frequency every year. There are a very small number of non breeding Black and White Casqued, along with a handful of Black Casqued and Yellow Casqued. There might be a very small amount of breeding going on, but if there is, it's very minimal.
For Asians, there is a small population of both Sulawesi and generic tarictic hornbills, fortunately both populations do have some degree of breeding currently occurring. There is a small but steady population of oriental pied. For larger birds, there is a small number of Blythes Hornbills, including one breeding pair and even some recent imports. A handful of wrinkled, but next to no breeding AFAIK. A few male rhinoceros hornbills are kicking around, and one or two rufous hornbills too, surprisingly. All are older and non breeding. There are also one or two pairs of wreathed hornbills as well, and possibly breeding too.