Ranger Ben led our tour, which we booked by phone the morning of our visit (we were able to get 4 tickets for an afternoon tour). We checked in at Yosemite Lodge to get our tickets, then boarded an open-air trailer with bench seats pulled by a semi-type truck and with a raised area for Ranger Ben to sit so that he could see us and interact during the tour.
I cannot say enough about what a nice job the ranger did in giving us insight into both the history of the park and the features of the area - from the surrounding peaks and waterfalls, to the trees and animals in the park. He was informative and interesting, and his delivery was smooth. He answered questions and made sure to point out a variety of things of interest, including rock climbers, tree varieties, and rock types. We made several stops for pictures, including a gorgeous view of some of the peaks from a bank near the river which was very picturesque; a stop at tunnel view; and a stop to listen to the river. The tour provided water to refill our bottles (recommended to take on the trip, as well as sunscreen).
We all enjoyed the tour, including the kids, and I felt that it was a great way to get a feel of what the park has to offer. There are many other things to see, but this is a good starting point.