Everything from books about theme parks to Roller Coaster Tycoon implies that parks need thrill rides (physical thrills) to balance out the slow rides. Walt was told something similar. In my dream park, I imagine disregarding this wisdom, and having NOTHING but dark rides (all of them slow, many of them Omnimover, etc).
In some ways, this was EPCOT Center 1982. But they did it on a grand scale without the smaller dark rides, and without the 'transportation' rides like PeopleMovers, monorails, skyways, Main Street vehicles. I'd want to include them in my dream park.
Of course, Disneyland 1955-1959 (pre Matterhorn) was like this, too. There was no thrill attraction (let alone a series of mountains), and I consider it no accident that it became world-famous quickly.
Can you imagine an animation park built out of nothing but Fantasyland style dark rides (bus bar, slightly better than painted flats) that leveraged the Disney characters, used the Disney songs, and placed you into each movie? Fantasyland rides always have lines - why don't they build like 30 more of these? At this point, they could almost do "continents" as lands, and place the Disney movies/darkrides into the continents that way.
Wouldn't it be cheaper to build 30 small dark rides than five "big coasters"? Anyway, a man can dream in the safety of his own skull