Seeing as crocodiles were around during the Mesozoic period, I'm thinking about maybe having a croc enclosure. There just happens to be a croc farm here in the UK also, so getting hold of some may not be much of a problem. These would be Nile crocodiles which can grow up to 18 - 20 ft.
Crocodiles are reptiles, so are you putting them with your dinosaurs or in a nearby exhibit so to portray a different environment? I think crocodiles and alligators lived even before the time of the dinosaurs, but look different than they do today. Supercroc could reach 40ft long, but Nile crocs are still pretty big. Will they be this size when you get them for the park or babies? They do take a long time to grow up.
I don't know yet what size they would be when I obtain them? I do know I would likely have them in a small enclosure on their own (unless I go for the Supercroc paddock idea) maybe similar to the one pictured in your last post.
Will you be hiring professional keepers to look after the crocs? You would really need to know what you're doing to avoid being eaten yourself! Anyone could just throw food into the enclosure, but what about cleaning and other general maintenance? How many are you going to have, and will they have something to go into for the winter? I think reptiles (even big ones like these) need heat mats or something warm, as they're cold blooded and have no way of generating heat for themselves. Although I might be wrong about this.
Purchase a mixture of ages? If you buy some adult crocodiles, some young crocodiles and try obtain some eggs from somewhere other than that farm then you'll have a diversity. The adult will be able to breed. The babies can (and should) be kept away from the adult, perhaps for visitors to view or touch. And the eggs provide a new generation and new genes into the group. You could get some animatronic Deinosuchus to place on a bank sunbathing and perhaps one submerged? As long as one of the females doesn't nest near them they should be fine to put in with them.
I would suggest gharials would be the ideal species as they look quite similar to sarcosuchus and they primarily eat fish and smaller animals making them much safer and easier to handle but they are critically endangered making them hard to come by and expensive. The next best thing might be a false gharial but they are known to eat deer in the wild so they will be more dangerous.
Gharils would be the safer option out of everything but if you want crocs you got to make sure they meet the right welfare enclosure which would be to make sure they have heat so is it indoor or outdoor that is the question