We recently did a tour with John to Yosemite. We tried twice to get into Yosemite with our RV, but the park was closed due to a massive snow bizzard, rock slides and power outages. We stayed at Groveland and decided a day tour was our only option as we couldn't put snow chains on our RV.
It turned out to be the best day. John has so much local knowledge and history about Yosemite, we could not have seen or leant so much in a day without him. There were four of us on the tour. We were all from Melbourne.
We would definitely recommend John and Yosemite Guide Service.