While Breezer has a good point, it's also very important to have a good return path to the park entrance. It's just as important to get peeps OUT of the park efficiently as it is to get them to your rides. A series of semicircular arcs with connecting radials, sort of like a spider web, all centered on the entrance, might be your best bet. So you have groups of 2 or 3 rides in the spaces between the "spiderweb". The disadvantage of this layout is that peeps might decide to leave when at the very back of the park, so take longer to get out. Another alternative is more like a clover leaf, or a wad of bubbles clustered around the entrance, to try to keep everybody as close to the exit as possible.
The reason getting peeps out of the park is so important is because the rate at which peeps leave is the rate at which money enters your coffers. It works like this:
1. Peeps and Money
Peeps start with a given amount of money. Because very, very few will ever use an ATM, by and large the only money you can collect is what they start with. HOWEVER, peeps do not leave when they run out of money. The duration of their stay is a function of elapsed time modified up or down by their happiness level.
Because of these facts, the VAST bulk of peeps (IOW, those who don't use ATMs) spend money at the rate of ( average starting money / average time spent in park ). It doesn't matter how you set your prices, or how efficient your rides are in theoretical $/hour, because peeps have a fixed amount of money and will be in the park a fixed amount of time. If you take all their money up front, they'll still hang around.
In general, starting money averages as follows:
* ~$75 per member of a teen-only group
* ~$90 per member of an adult-only group
* ~$95 per member of a family group
In general, the amount of time a peep will spend in the park can be related VERY APPROXIMATELY to park rating. You can expect the average peep to stay in the park about 1 hour per 2500 park rating. This is nowhere near exact but close enough for planning purposes.
2. Park Capacity
All parks have a capacity of peeps. This is either the "natural" capacity or a (lower) arbitrary cap set by the player. The "natural" capacity is a multiple of the park rating which varies by difficulty level (ex. 150% at easy level, less at hard level). Once a park reaches its capacity, it enters a steady state condition. No new peeps can enter before some old peeps leave to make room for them. Thus, the rate of new money entering the park, which effectively defines your monthly income, is the rate at which old peeps leave the park, so you want it easy for old peeps to leave.
So what happens is (assuming you haven't capped capacity), every time you add something to the park, you increase the park rating and thus the park's capacity. If the park was already at its old capacity, suddenly there's room for a bunch more peeps, so you get an immediate surge of new peeps entering, and this creates a spike of income, especially if you charge a lot for admission. However, then the park reaches its new capacity and you just get a trickle of new peeps entering as old peeps leave. There are now more peeps in the park than before, so more of them will be deciding to leave per hour. However, they'll also be staying longer than before because the park rating is now higher. Thus, the equilibrium peep flow, and thus your income stream, won't show much long-term improvement after the initial surge.
Thus, you eventually get into diminishing returns. Adding to the park provides an income spike but has little effect on long-term, steady state income when the park is at capacity. And adding to the park increases operating costs, which eventually exceed whatever long-term steady state income you can generate. Getting old peeps out quickly so new peeps can enter helps stave off the diminishing returns.
