Great Grapes was a cool little festival, especially because I had free tickets (Thanks Yelp)! I thought the price of $25 to get in was a little steep, but probably worth it if you love wine. There were several local wineries offering wine tastings and sometimes little snacks. It got a little hot standing in the sun with the huge crowds of people trying to make it to the front of the line for tasting.
Besides wineries there were a few other booths set up selling knick knacks. Plus there were some food vendors selling fair type food (curly fries, funnel cakes, etc). To top everything off they had several different bands playing some decent music throughout the day.
This festival is a fun time. If you plan on going next year make sure to take a blanket and/or chairs to sit out in the lawn in front of the stage. It might also be a good idea to pack a little lunch especially if you plan on staying all day. Not only will you get hungry but the food will help soak up the alcohol. Just be prepared to spend a lot of time in line waiting for your free wine tastings.
I almost forgot to mention that you get a commemorative wine glass (included with admission) to take home. Bonus.