I would like the ability to create kids rides as well as adult rides. Hopefully there will be waterpark features as well, slides, wavepools, water coasters, etc.
Also, is this going to be available for MAC?
Also, as mentioned by other users, all the latest and greatest coaster designs and flat ride designs should be incorporated. The ability to make games for the sims to play and restaurants for them to enter and eat at. As close to a real theme park experience as possible.