For some reason, out of everything Disney has ever done, Epcot Center has definitely affected me the most.
Which is weird, when you think about it; for most, the de facto disney experience is classic Americana; getting an ice cream on main street, the wonder of seeing storybook characters brought to life in fantasy land with that wonderful disney twist, or the occasional only-in-WDW high-quality thrill of the "mountains".
For me, the essence of WDW was Epcot, which at the time offered a different flavor of americana; progress and a look at the future. For some reason, I connected with Epcot in a special way. I think it has to do with Epcot Center's biggest advent, which was the unprecidented amount of interconnectedness. Name one place on earth that has achieved the level of sophisticated interconnectedness Epcot Center once upheld. I'm of the belief that such parallel connectivity appeals to us all on a very basic level. Undeniably, there is something inherently appealing about many components of a whole which are similarly formatted but unique in their own way; take Ghostbusters for example (bear with me on this one) - each team member wears the same uniform and backpack, yet the name on the uniform tag is different, and each brings to the team their individuality. It was the same at Epcot Center. The Universe of Energy dealt with fossil fuels. Fossil Fuels powered the cars at World of Motion, which we drive in towns and cities that may one day look like the ones depicted in Horizon's environments. In Horizons, we catch glimpses of an undersea city that echos Sea Base Alpha of the Living Seas, and food dispensers and irrigation systems that mirror those found at The Land. All 3 pavilions of future world West had the same, fantastic appearance; murals and decorations in the land and Journey into imagination evoked the same feeling as that found in It's a Small World, and approached looking at the future from more of a light hearted point of view.
The most important thing, however, is that as a young child (starting at age 3 and onward), I actually was AWARE of these parallels. Maybe not enough to express them verbally as such, but I could tell that everything was related, and not accidentally either.
Grizz mentioned serenity - that was my favorite aspect of the place. Unlike M:S and TT, the pavilions of Epcot Center didn't demand anything of you like 6 flags rollercoasters did. There was no tense moments before the ride starts, no courage mustering, no fear. As a young child I was afraid of scary, fast rides and didn't want to have anything to do with them. At epcot, I was safe. Each ride held enough art and detail that I could ride them forever and not catch quite everything. Plus, I was obsessed with futuristic looking things, and of course epcot was the epitome of that design style.
A final word about the irony of the possibility of making SE a rollercoaster. When I was very young, I was petrified that when the cars turned backwards they'd drop fast. My parents reassured me that it was safe, and they were right...but if things keep going the way they are now, it's as though my worst WDW fears might come true one day yet.
..sad.
-Brian