Margaret River reds are sub-standard, but you can still get a good "MR Red"
I liked Watershed, and some place that had a 'Kisschasey' (named after the band) wine... the vineyard was Swings and Roundabouts. You can get their wines locally here in the east, I don't mind them at all.
I was also gobsmacked by the real estate that Voyager takes up - absolutely immaculate. Their reds weren't bad, but I felt compelled to visit just to help them pay their maintenance bill.