The best times to visit the Barossa and other South Australian wine regions are in the spring (Sept-Oct), when it's not too hot and there are plenty of flowering trees and shrubs, and in the fall (Apr-May), when the leaves turn red. The main wine harvest is in late summer and early autumn (Feb-Apr). The least crowded time is winter (June-Aug). Hotel prices can be more expensive on the weekend and many insist on a minimum 2-night stay.
Note: This information was accurate when it was published, but can change without notice. Please be sure to confirm all rates and details directly with the companies in question before planning your trip.