Here's my Just Back Report for our road trip Melbourne to Adelaide in the Christmas Holidays (2 adults). Thought it might be helpful for people doing a similar trip. Sorry it's so long. I haven't gone into detail so any specific questions about wineries, accommodation, distances etc feel free to ask.
Day 1: Melbourne to Warrnambool via Great Ocean Road.
Left 8.30am, took Westgate bridge and highway to Torquay and along the GOR. We have previously done the GOR so didn't stop as much this time. Stopped in Anglesea and swam at the beach - very nice and not crowded at all. Good bathroom facilities but could be difficult to access the beach for handicapped/limited mobility people (down a steep hill). Next stop Lorne - had a coffee at the surf club, swam at the beach. Much busier here, but lots of room for families, plenty of parking and picnic facilities. Had a few quick stops for photos along the way to Apollo Bay - another beachside town with a nice beach. Picnicked here for lunch - lots of grass to sit on near visitor's centre. Toilets and picnic facilities here too. Next stopped at a few sights like the arch, london bridge etc and the 12 apostles. Saw 3 koalas on the drive through the Otways (1 baby) and an echidna within touching distance (but don't touch!) at one of the photo spots. We were too early for the penguins at London Bridge. Pushed on to Warrnambool where we camped at Discovery Holiday Parks (clean, plenty of shade, close to beach and near a holiday funpark with a few kids rides). Had dinner at the RSL (great view over the water from atop a hill, HUGE servings but not as cheap as expected - about $20/main).
Day 2: Warrnambool to Penola via GOR and Mount Gambier
Drove along the ocean as far as Port Fairy (stopped for a swim at South Beach - nice beach, steps to get down) then cut up to Mount Gambier, saw the Blue Lake - very nice and blue, drove up to Penola and straight to the Coonawarra Wine Region. It's very different to other regions as the "terra rossa" is only about 2km wide by 20km long and the road runs right down the middle. So wineries are very close to each other on either side of the road. Makes touring very easy but also a bit boring in my opinion. Definitely worth visiting though if you like your red wines. Stayed at Penola Caravan Park (very basic facilities but clean, some shade, nice grass and friendly owners - try and get a spot away from the road as the trucks are noisy).
Day 3: Penola to McLaren Vale via Hahndorf
Drove through the hills, stopped in Hahndorf for a frolick. Cute town, definitely worth a quick stop. Lots of little shops, plenty of great looking pubs and good food to buy. If we had more time would have done the Beerenberg farm (strawberry picking, try produce etc) and had lunch at a pub. Unfortunately waited 15 minutes at chocolate shop no 5 and wasn't even acknowledged so left without being served. Got a good German hot dog from the shop next to Caltex petrol station, visited Udder Delights Cheese (they do picnic hampers and cheese with matched wines to try at wineries) and had some home made ice cream. On to McLaren Vale where we struggled to find accommodation - ALL camping grounds were full so stayed at Christies Beach Hotel/Motel. $100 for an ocean view room which was basic but clean and newly renovated. Stopped at Geoff Merill wines - one of my faves, then to main McLaren Vale area to do other wineries. I found it more interesting than coonawarra and a nicer drive. Focus here is on Shiraz though while Coonawarra is mainly Cabernet. Went to Christies beach for a swim, and had fish and chips overlooking the sunset at picnic tables outside the surf club. Very nice.
Day 4: McLaren Vale to Barossa via Adelaide
Our room was supposed to include breakfast but they "forgot to deliver" it. We had breakfast at Blessed Cheese - quite nice, coffee wasn't too bad. They also do cheese hampers with wine match suggestions, but we just got a take away cheese plate to have for lunch later. Stopped at Glenelg beach for another swim and to watch the beach volleyball (we both play) - State Open was on so good to watch. Water so warm! Then on to CBD for quick drive through - not much to see.. and out to Barossa. Only a 1 hour drive from the CBD. As we had limited time, we found the most efficient way was to get a winery map from the visitor's centre - circle the wineries we wanted to see and plan a route based on closing times of the wineries - worked well. We stayed at Tanunda Caravan Park - very nice, lots of shade, big oval for sports and tennis courts. Across the road from a public swimming pool and close to 10 pin bowling and mini golf.
Day 5: Barossa to Naracoorte
Visited a couple more wineries in the morning - can highly recommend Tscharke's Place - a boutique family owned winery with lots of great reds and very friendly service (i.e. VERY different from Jacob's Creek, Wolf Blass and Penfolds). Drove to Naracoorte - arrived at 5pm when the caves were closing, so we stayed at Naracoorte Big 4 caravan park (very clean and renovated facilities, backs on to a HUGE man made swimming lake (chlorinated), some shade and good cooking facilities).
Day 6: Naracoorte to Melbourne via Grampians
Visited the caves in the morning - plenty of tours as it's the holidays. Saw Alexandra cave which I can recommend to people who haven't seen many caves. Very nice and pretty and very open so not bad for claustrophobic people. There are many more caves you can visit - 1 is self guided but the rest are all tours. The place is most famous for the fossils of megafauna they found in the caves so do see them if you can. The tour guides we had were very friendly, entertaining and well spoken. Drove out to the Grampians National Park, walked down to McKenzie Falls (there's a viewing platform at the top relatively easy access although a short steep hill, the rest of the walk is 1km return down to the base, quite steep and lots of steps so not for the unfit/immobile), then to the Lake - don't bother! The drive through the mountains was very pretty though, and gives a nice contrast to the relatively boring landscape for the rest of the way to Melbourne :) Got back to Melbourne 6pm for NYE :)