Money/budget Management ideas
I believe money should be the main underlying constraint that sets objects, either player defined or mission generated. I would like to see the control of your budget.this could manifest itself in many ways. You could have different budget for different types of items, Rides, Shop, Research, infrastructure (paths/car parks/trains). Could renegotiate the budget with sliders to keep it accessible.
anyway here are a few ideas i would like to see if possible.
Upkeep
Think city builders, each ride/show/scenery has an initial cost and an upkeep. With bigger more expensive rides and shows having the biggest upkeep. The more cars/trains on a ride means you need more staff which is the reason for the upkeep.
This is the key idea to money management games. This would have a big impacted to how the player chooses what to do next.
Pricing
The player will be able to price each age category separately for entry. How much each group is willing to pay for entry will reflect how well the age group is catered for, this could make people think about mixing their rides and attractions better.
Making Money
After parking and the entrance fee, food and merchandise are the best way for you to make money (if rides are free) . The cost/profit ratio will be very high on the food and merchandise. I would like to see food etc. handled in a more in depth manner (i know that it is not to everyone's taste) when you build stalls or restaurants (please have restaurants) you should have to negotiate for stock. or to keep it simple for more casual gamers or for people that just want to build coaster then you could have a catering services that does it all for you for slightly less profit. then all they would have to do is build empty stall and restaurants (please have restaurants). this could also play into a future objective system.
Future money making (maybe DLC)
Make your park so good that people will want to stay on site, in your very own hotel($). I would like the game to expand into this direction, so the player gets to manage a whole resort.