“Over-the-top” is good in this case. It would have been a drag if it looked like an actual zoo. The “theater of the absurd” is a standard approach Rivera has used in her stories, and a good approach (as also seen in literature and movies).
Tiger Touch Center must be a fairly exclusive zoo if Tess Tigress really has the time to personally welcome every arriving guest. Kind of like Mr. Roarke on Fantasy Island. And like an island, this place looks to be in the middle of nowhere.
While wet-blanket Mark takes on a pose of indifference, Diana curiously remains a silent and ignored partner. Is this a strategic pose on her part to encourage Rex to bond more with Mark? It seems likely, given her admission to Mark when she picked him up at the airport.