I was trying to think of a cool reason to cater to a specific guest type as right now its just what happens to be in your park and there is no reason to go for one type unless told to by the game. There should be some sort of rewards for hitting certain percentages in your park. if you hit 30% nature lovers, unlock some decoration of a Trike or something. If 50% are thrill seekers, unlock a new attraction that is geared towards them like a rollercoaster. Maybe at anything higher then 85% you unlock a specific Dino that can be discovered that is the "ultimate" dino for that group. This would give users different ways of playing the game as a nature park that hits 85% only nature lovers would look very different from a thrill park with lots of carnivores.