At the top of the list are bathrooms and plenty of places to eat and drink. Make sure you have bathrooms scattered throughout the park, particularly in close proximity to food stalls and nauseating rides. Although you can charge your guests for the privilege of relieving themselves, charging more than a dime for the use of your bathrooms may result in guests deciding to relieve themselves on your footpaths instead. Give your guests plenty of places to eat and drink and be sure to set benches near these locations so that they can enjoy the food you've just charged them an arm and a leg for. Provide your guests with attractive, comfortable surroundings near food stalls.
Guests have other needs they are willing to spend money on as well.
Umbrellas are a necessity when it rains, so be sure to have them available by building an information kiosk or souvenir stall. A balloon stall will bring joy to the children in your park, and photo opportunities on rides let your guests take home a picture memory of their thrilling ride on your roller coasters.