We had a great experience with Nick as our guide on the Yellowstone full day tour! He was super knowledgeable, enjoyable, had obviously done his homework and a lot of research on the area (geology, park history, animals, etc), and was very attentive to our individual needs and our needs as a group, offering options whenever possible. Not that the guides are responsible for ensuring you see wildlife, but we got to drive slowly through a herd of bison, at one point having to come to a standstill while many ran or walked by just feet away! Outside of this, our favorite site was grand prismatic springs. The tour company provides ample food and water, and the large van was well air conditioned so we were very comfortable, and it was great to be picked up and dropped off at our hotel.
We went with family, but no children. My cousin and I took our mothers who are in their early 70s.