A while back, I took a tour of Vina Santa Cruz, owned by the same person who built the Hotel Plaza Santa Cruz and the amazing museum (more on that at a later date)- Carlos Cardoen (he owns half the town, actually).
The vineyard is pretty spectacular, set in a stunning valley about 15 minutes from Santa Cruz, camino a Lolol. Along with the typical tasting, the tour includes a short bubble-lift ride up to the top of a hill, providing fantastic views of the vineyard. At the top, there's an interesting outdoor mini-history of Chile from prehistory, through to the native Mapuches. The vineyard also boasts one of the largest private observatories in the world (night tours are offered).
You can book a tour in the hotel or via Ruta Cruz. Recommended.