Firstly, if your driving out here you have to be a member of RAA (NRMA, RACQ, RACV etc) I had a catastrophic breakdown, was towed by a friendly local 160km into town, then the RAA paid for my car (to be trucked back) and my fiance and I to fly back to adelaide (we paid the extra $20 for the plane instead of an overnight bus trip).
So, Cooper Pedy.
The Food is really good. There is a little greek resteraunt (Tom and Mary's I think) at the top of town that does very tasty beefteakia . Then down the hill is a resteraunt with a fully enclosed and air-conditioned veranda that serves up Amazingly good pizza.
The Old timers mine is worth a look to see how things were done back when'.
Every second building sells opals, just be ware of the cheap ones.
Groceries are actually quite reasonlably priced, a lot of it cheaper than in Adelaide stores. The locals were really friendly, but...as far as a destination I would limit it to an overnight stop with an hour (or more) to check out the old timers mine stock up on supplies and have a good meal and rest. There is honestly not a lot else to see or do.