Used the ubiquitous Groupon deal to visit Treehouse Vineyards awhile back. I really enjoyed hearing the story of the vineyard, seeing how their bottling has changed, taking in the grounds, and sampling the wines. The wine itself is very sweet - so it helps to know that going in, especially if you prefer drier wines. I love that all of the wines' names have corresponding stories significant to the owners. The wine-a-rita (wine slush) was the highlight for me. I've only been in the afternoon, but I've heard great things about their live music in the evenings.
As many others have mentioned, you'll probably think you've made a wrong turn, somewhere between the flat residential area and huge cemetery, but then all of a sudden you see the vineyard sign, pull into the drive and it looks like you've entered a different world.
You really can't beat the Groupon price, and we enjoyed a fun afternoon learning about this local family business.