If it is a large park then make sure there are information kiosks so the peeps can buy maps, and if you have th eexpansions then passport machines can be used to encourage them to areas far away from the park entrance.
In my experience, selling maps in a large park is detrimental to ridership, due to an apparent flaw in the guest AI. The logic is something like this:
1. A guest without a map can only "see" attractions within a certain distance from his current location.
2. A guest with a map can "see" every attraction in the park.
3 When the AI goes to choose an attraction, it chooses one (apparently at random) from all of those that the guest can "see". So, the choices for guests without maps are much more limited than for those with maps.
4. If the guest has a map, the AI doesn't seem to consider the guest's current position in the park when choosing a ride. It is not at all uncommon for a guest to choose a ride that's all the way on the other side of the park, even though there is a similar ride right next to him. I have seen guests do this time after time, trekking from one side of the park to the other.
5. Guests don't seem to be able to recognize "transport" rides as actual transport. They are no different than any other ride; guests only ride them according to their excitement/intensity/nausea tolerances.
So, you have a scenario like this:
1. Guest enters the park and buys a map.
2. He sees your big "feature" coaster all the way at the back of the park.
3. Even if he is only two steps away from the queue for your monorail to take him there, he proceeds to *walk* to the coaster.
The net result is that in a large park in which maps are sold, it won't be very long before your paths are jammed with guests walking from one side of the park to the other, and very few of them actually queuing for rides.
So:
1. Do *not* sell maps at all.
2. Distribute a good mix of attractions and facilities throughout the park so your guest can "see" different types of rides no matter where they are, thus creating a "visibility line" that allows your guests to move farther and farther into the park. It also helps to place your entrances and exits so that the exit paths dump your guests back out on the "main drag" near a different selection of rides instead of back near the entrance of the ride they just lef.
3. Build a couple of transport rides from the entrance to the farther regions of the park.
When you first open the park, the attractions near the entrance will be very crowded but before too long, your guests will "percolate" throughout the entire park and your rides will get a *lot* more business -- they're spending more of their time riding rides instead of walking around from one to another.
Final note: Don't build monorails, steam trains, or other "transport" rides with more than two stations. Due to a bug in the game, such rides with more than two stations will soon become completely filled with guests who can't get off until you close the ride. I'm guessing that this is due to some sort of logic that allows a guest to get on a ride at one station, then get off at any other station they choose (which makes perfect sense), but it doesn't work right. If there are only two stations, the trains empty completely at each station. If there are more than two, any guest who doesn't get off at the next station after he got on is stuck on the ride forever.