If there was an overarching theme to the ones that were new to me, it was darkness. Disney's people really like to use low light or even total darkness to kick something up a notch. Here's somebody's nice video of maybe the most famous coaster at Disney World, 1975's Space Mountain, which is inside a weirdly stylized conical building in the Magic Kingdom's Tomorrowland:
It's actually much darker in there than that low-light video implies; even the "space station" diorama you see going up the lift hill is suspended in dim murk, and the ride proper is in near-total darkness. With the lights on, you can see that it's a not-very-extreme coaster with a layout inspired by Disneyland's Matterhorn Bobsleds. There are actually two mirror-image copies of the coaster inside the conical ride building. The ride's not very fast, the drops are pretty small, and most of the thrill comes from the rather jerky turns and dips and the fact that you can't see them to ride defensively.
But then there's the presentation. The queue and loading station are themed like some sort of interplanetary spaceport, and the beginning and end of the ride involve passage through tunnels of pulsing blue and red light with throbbing sound effects. There are also more subdued light and sound effects inside the mountain while you're riding. There are even few futuristic dioramas to look at while you're walking through the tunnel back to Tomorrowland after getting off the ride.
Most people seem to think the one at Disneyland, which was built slightly later (and extensively refurbished not long ago), is a better ride: it's a single, higher-capacity coaster with, apparently, more comfortable cars. I haven't ridden that one. Recently it was given a Star Wars-themed makeover that turned it into "Hyperspace Mountain"; that hasn't been done to the original in Orlando.