We are leaving Perth in about 4 weeks towing a Supreme Territory caravan heading across to Adelaide, up the middle to Darwin, across to Broome and back down to Perth or should we go the other way, ie from Perth up to Broome, across to Darwin, down to Adelaide and across the nullabor to Perth ?.
I would head north first, that is up to Broome, because it will be pretty cold at this time of year in some of the lovely spots on the south coast of WA that you may want to visit like Denmark, Esperance and Albany. It may also be a bit chilly at night in the Flinders Ranges at this time of year too, although the cooler climate is good for bushwalking. If you headed north first and then back south again around September time, you would certainly have better weather to enjoy the south coast. You haven't said how long you're planning to travel - but I was in Broome a couple of years ago in August and it was really crowded. There's a lot of markets and festivals there at that time, but it's best to book a van park in advance if you can.