Some great suggestions here.
I'm a fan of Margan family wines as well.
I am also a member of Keith Tulloch's fan club (well, wine club member that is! lol) and also of Peterson's of Armidale.
Whilst Peterson's send us wines from their other vineyards in the Hunter and Mudgee, it is Armidale we have been fans of for the longest, in fact, we're amongst their first membership of the wine club established there. Peterson's of Armidale do produce some very good cool climate wines, check them out if you're ever passing through. The vineyard is on the old Dangar property and so has a bit of history to it as well, the cellar door is based in the old stables, which is not just any stable I can tell you!!
Meanwhile, we like Keith Tulloch's wines and he does some of the best Hunter Semillion you'll ever get to taste. In fact, I think one year his Semillion made the world top 10. I love that every year they give us the opportunity to come down for a Master Class, which basically lets members have a tasting of Keith's varieties over several vintages. Keith also is there to give some great information on the whole process of wine making and they often put on a great lunch as well, for members, its a freebie!