^Yes, i do. This problem happens every time you try to make a custom scenario. The problem could be one of a few things. Usually, its because the peeps become inpatient. If you open the park right in the beginning, they want things to happen right away. Since you build in "time", you cant build fast enough to keep them satisified. They run by statistics so if its a big park, they want big results fast.
Another reason (happens to me) is because they get lost. If you have a plaza or something, they will usually cluster and not find their way out because they have severley low AI. They get tired so all you need to do is temporarily cease operations and build one path out of the bad area directly to the front entrance so they can leave. That will boost it immensly.
Smarter peeps in RCT3 I have to agree with! I have all the games with all the expansion and 3 is the best attraction wise and peep wise. RCT2 is amazing also sice it has some Six Flags parks in it, but the peeps aren't that smart in it. They get lost easily and complain about every single ride because its too intense or too boring. But that mostly happens in the 1st one though.
Top 3 Steel Coasters: 1. The Incredible Hulk 2. Maverick 3. Dragon Challenge (Fireball)
Top 3 Wood Coasters: 1. The Beast 2. American Eagle (Red) 3. Hades