My husband and I recently had a day with Ian on the Wine bus and enjoyed the experience very much.
Ian was a great guide, and the places we visited were in lovely locations and gave a very informative overview of all of their wines and the vineyards they each have.
The lunch at Tokar estate was really nice, and the chance to go to some established places like Chandon and then a new estate like Helen and Joey's was a really good mix.
The Yearing visit was also good and the cider tasting there is a must (buy a chilled bottle for $7 to drink there).
The whole tour is quite informal (it doesn't need you to be a wine buff to enjoy) and Ian does a good job explaining about the wines and the region, allowing enough time to sample plenty and make the most of the day.
Would definitely recommend this tour to try some wines and see some of the Yarra Valley as well.