While dinosaurs are absolutely the priority and I'd rather see them fleshed fully out than the guests, it would make the 'zoo/park' bit of the game feel a bit more satisfying if there was more visual variety to the guests.
Even just an updated palette of shirt colors that guests can spawn in as would work! (seems that the shirt store only has blue shirts in stock at the moment... lol)
Additional idea: A very small chance for guests to occasionally spawn in wearing an inflatable dinosaur costume. Just imagine it. Would be incredible lol