oh boy...im gonna give you guys a headache...
More Dinosaurs
Hotels
Should be JP Styled, and have a Helipad at the top for emergancy evacuation of visitors...
Security Centers
better versions of Ranger stations. they have wranglers in them, as well as choppers. should have an emergancy helipad for visitors to escape the island if a major escape happens
Marine Security Centers
like the one above, except it has boats and mini-subs to help vaccinate the marine reptiles, if they're added. oh, and no escape chopper [how'd you get a chopper to lad on a pad that's 10 feet below the water?!

]
Breading without Hatcheries
read the lower suggestion to find out what i have in mind with this
Off-Island importing of Dinos
sort of like the bit in JP, where Hammond Mentions the Dinos are brought from Site B, and put into the exhibits. we could have the dinos (pairs: 1 male, 1 female) brought in from Site B on the first time (open a window which asks you which dino you want, and you select, and chose 1 male and 1 female), and after that, keep the park dependant on the dinosaurs' breeding. some dinos, like Rexes, Gigas and other very large, very powerful super preds should have very low breeding rates, so you dont end up with islands crawling with 100+ Rexes

. Herbivores that make up the Predators' main diet should have relatively high breeding rates. Raptors have among the highest breeding rates, with only Compies [if included] and small herbivores topping them.
Colour Variation between Genders
Have the males more vibrant than the females. in the super preds' case, make the male a slightly darker [but still more vibrant] colour pattern.
Museums
When a certain dino in your park dies, and it drew in major popularity in life, you can take it's skeleton and use it for display. making it so that some dinos get permanent scars in fights would make this even more interesting. each museum should have about 5-10 spaces for dino skeletons.
Underwater tunnels
Hallway underwater, with a thick glass cieling [sorta like a pipe underwater, made of glass. the ones that some Aquariums have]. they are used to view the Marine creatures in the park.
Visitor view
Anyone who played Zoo Tycoon 2 knows what i mean. this view puts you in the eyes of a visitor, as if you are actually walking through your park. to make it more appealing, the skins on visitors need to be better. It would also be a good idea to boost the details when you enter a museum, with certain set spots in the museum to place dinos. lets say 5 different spaces to put the skeletons of dinos, all in very high detail, split from the main game by a loading screen. it would be like FPS Games, but without a gun. this view allows you to take pictures as well, to use as screen shots for your desktop, or even the background of the main menu of the game. the super high detail bit should be implemented on all in-door places, so that, if you went into a Marine Tunnel, Museum, or any other building that is added [must be special. not going into food stands or gift shops. they stay at a medium level of detail, and are all the same, to save the work and time of making several differently skinned high detail copies of the same building], youd feel like you were actually there.
Genetic modification
Allows you to occasionally modify the dinos [has a high price tag. up to $100,000 in game], to make a single, unique attraction. you can modify looks, longevity, strength, size [im sure everyone knows why i suggested these

], and several other things. maybe BT could have a look at similar technology that made games like NFS: Carbon so popular and versatile when it comes to customizing things.
Pack behaviour for some dinos
should also be one of the possible features with the Genetic Modification idea: how likely the creation is to pack with others of it's base species (the dino that was used as a base for the creation).
Intelligent Raptors
they should obviously communicate, and do things like ambushes. they should also be able to enter buildings [good luck escaping if your in visitor view

]
Set Scar points
Dinos that are well known [Rex, Raptor, Steg...etc] should have some set scar points, so that when they get into fghts and are wounded, the wound shows on the scar points. for example, Rex gets a slash over the snout's right/left side, or on the eye. if possible, all dinos should have scar points. if not all, at least the well known ones should get them.
these are just starters. if i get any other really interesting ideas, i'll mention them

.