I have only done the World Showcase one. Starts in Innoventions or whatever they call those buildings in Future World.
First, you pick a helmet thing (which they require you to wear) and watch a video. I think it was a safety video. All I really remember is that it was very boring.
Then you learn how to use the Segway: how to balance yourself on it (hardest part for me!), how to go forward, around cones, how to stop, etc. Then you head out to the World Showcase.
It's a lot of fun riding the thing through Epcot. You ride through parts of a couple pavillions that you wouldn't think you'd be taking a Segway into. I really enjoyed the riding and especially enjoyed the little bit of free time.
We stopped to have our pictures taken in that little space near Italy - the one they always block off for private parties when it is time for Illuminations. You can take your own pics of each other or the guy will take it for you.
You have to stop and listen to a tour guide talk about the pavilions. If you're interested in an actual tour of the World Showcase, you'll appreciate that...but there really isn't enough of time spent doing that to get too in-depth.
I really think they should have two tours: one walking tour for info about the World Showcase (and better than the old "Hidden Treasures" one) and another just for zipping around on the Segway. Just MHO.
I took the tour because I wanted to ride a Segway. For me, it was "worth it", but that's one of those things the differ from person to person. Next time, I'll take one that focuses more on the riding and less on a tour.