What do you think of the difficulty of the original RCT1 scenario's? While its obvious that on average the earlier levels are easier than the later ones, a few late ones (such a Paradise Pier and Thunder Rock) just appear much easier than the surrounding scenario's.

If i were to rate the difficulty of the scenario's (which i did =p), I would use the amount of guests I by the end of the scenario relative to other scenario's that have the same time. (as a more difficult park makes it harder to build attractions and therefore attract guests). I have made a table with how many guests I got by the end of every scenario ( here ) and some scenario's got noticeably fewer guests than others (mostly Mystic Mountain , Lightning Peaks and to a lesser extent Trinity Islands). Judged by guests count, I would classify the parks like this:

Very easy: Forest frontiers, Leafy Lake

Easy: Dynamite Dunes, Diamond Heights, Evergreen gardens, Bumbly Beach, Katie’s Dreamland, White Water Park, Pacific Pyramids, Paradise Pier, Thunder Rock

Moderate: Trinity Islands, Millennium Mines, Karts & Coasters, Mel’s World, Crumbly Woods, Ivory Towers

Hard: Pokey Park, Mystic Mountain, Lightning Peaks, Rainbow Valley

Hard is ofcourse relative to the other parks, as calling any scenario (except maybe Rainbow Valley) hard compared to the expansion pack scenario's is quite a stretch.