Mt Gambier is also a great option. I stayed at the Barn steakhouse and accommodation, we initially caught a taxi in (not overly cheap), but when the owners found out we flew in they drove us back to the airport and even offered to lend us a car next time.
Further afield, Kangaroo Island is well worth a visit. Aldinga is beautiful and right at the doorstep of Mclaren Vale. I can also recommend a great winery tour operator there as well (PM if you want), they'll even tailor it to suit you if you want to make it more of a micro-brewery tour
If you want to head south instead, Flinder Island is always nice too.
East has plenty of options and is quite scenic, Merimbula is always a great option and everyone is super friendly.