On balance, this was an excellent tour: well-organized, well-explained by the guide (Marco), and full of amazing wine, architecture, and food.
Directions to the pick-up spot were easy to follow, and Marco was there to greet us on arrival. We traveled in a group of eight (plus Marco), in a very comfortable Mercedes passenger van. (Note: it was very warm when we visited Vienna, but Marco was incredible in keeping the van very cool and inviting throughout the day.)
During our drive (approximately 1 hour from Vienna), Marco explained a lot to us (using an excellent microphone and speaker so that everyone could hear), about the wine region, the history, and how the varietals had subtle differences.
The two wineries we visited were picturesque, inviting, and INSTAGRAMable. Marco was great in his explanations of each wine, eliciting our comments, and answering any questions we had along the way.
For lunch, Marco took us to a traditional "heuriger": essentially a wine restaurant with picnic-style lunch. Most of the people surrounding us were locals or Austrians on holiday. It was a wonderful way to experience Austrian culture outside of Vienna, and sample more wines (and traditional cuisine). My wife is a vegetarian, and even she was able to find delicious choices on the menu.
After lunch, we took a beautiful cruise along the Danube for approximately one hour. It was pleasant, relaxing, and an opportunity to enjoy some sites outside of Vienna in a very chill atmosphere. The boat had indoor and outdoor tables, with A/C, and a full menu (in case anyone was still hungry after lunch!)
At the conclusion of the boat ride, Marco met us and drove home, but made quick reference to the Melk Abbey. (Note: the fine print of the tour mentions this but I didn't pay attention to it until we got there. The tour of Melk Abbey only takes place in the winter months. I'm not sure why, but the Abbey tour is not part of the summer experience.)
We returned to Vienna approximately 9 hours after our original departure, and had a pleasant experience. Again, Marco was an awesome, personable tour guide and driver, and I would recommend this tour to anyone who is looking for an outside-of-Vienna experience for a day trip, who enjoys dry white wines.