If you follow one of your Security Guards, you won't see any high-action crime drama. Security Guards stop vandalism simply by being present and visible inside your park. The prudent approach is to hire one Security Guard as soon as you open a new park. That way, your guests will know he's around and frowns on bench breaking and other such activities. Entertainers You won't find Entertainers very important as you build your park, but you'll want them later on, as the park grows.
Entertainers perform two major functions.
First, they can increase guests' happiness levels as they queue for a ride. Apparently, kids get happy out of sheer childhood innocence when they see an Entertainer and adults get happy because it's not them inside of that hot costume. Second, your Entertainers boost your Park Value. But RollerCoaster Tycoon will see you coming a mile away if you try to fill your park with Entertainers. Park Value will rise and then level off after about ten Entertainers.