I booked two days of a private tour in Vale dos Vinhedos with English-speaking guide, Morgana, and had a great time!
I stayed at the Hotel and Spa do Vinho, which Morgana picked me up each morning. She was always friendly and eager to learn about my experiences and share the history and culture of not only the region, but the individuals vineyards and Brazil as a whole. She was very flexible in helping to shape the itinerary of which vineyards to visit based on my preferences. We were able to cover a broad spectrum of what this great region has to offer, including a general look at the scenic vistsa and lookout points of the surrounding region. I ended up taking 14 bottles back to the US with me, and Morgana went above and beyond in helping me coordinate shipping/packing methods and purchase an extra suitcase.
Gustavo at GNB headquarters was also very accommodating and communicative, responding quickly and working through payment processing issues.
Side note: I booked my second day on very short notice - it's always helpful to know which vineyards/areas you want to visit with at least a few days notice for the best experience! Ran into some hours/tour availability issues!