I went solo this past may and did three tours (KTTK, Around the World on a Segway, and Backstage Safari).
KTTK was the most informative of the tours. We had a really great guide (Cory). There was a young girl on the tour celebrating her 16th birthday that day (finally old enough to take the tour and was so excited) who was a Disney Trivia fanatic. Cory had the barbership quartet sing Happy Birthday to her. She and Cory were constantly trying to stump each other and teaching the rest of us in the progress. We only got to ride Pirates of the Carribean and Haunted mansion, but Cory told us alot of stuff about the other rides. I've heard that with some guides you don't get to see that much of the utilidors, but Cory didn't rush us and took us all over down there. We saw quite a few characters half dressed, including the group of Pooh characters that were getting ready to go up to the CP. Cory did make a comment that the first tour of the day was always his favorite because it nearly always has fewer people in it, so he can have more interaction with everyone. He really loved his job and it showed. He also showed us alot of hidden Mickeys.
The Segway tour was ALOT of fun. There is only about 10 people in each tour. You spend an hour learning to ride it and then the second hour going around World Showcase. In Italy you get a break and can either get off the Segway or can ride around on your own. The guide told us a few interesting facts about each country, but the tour is mainly about riding the Segway. The Segway is not that hard to ride and we all were comfortable within about 45 minutes, so got to spend a little extra time in World Showcase.
Backstage Safari was just OK. I would not repeat it. We did get to pet a white Rhino (named Harley, because he was born during Harley Davidson week) and also a spiny lizard. We also got a personal tour on Kilamanjo Safari without the Big Red/Little Red spiel and the driver stopped a couple of times (or at least slowed to an almost stop) so we could get alot of pictures.
Again I was solo for that trip and surprisingly never felt out of place. In fact on all three tours there was at least one solo.