Hi Stuart
Carp on the fly in the Camargue would be my choice! The place is epic, and the area is wonderful, stunning old towns, superb food. I fished for carp on the fly there - some of the best fishing I've had anywhere!
You need local help to get to the carp fishing, the guide we used fishes for them like you stalk bonefish. There are other types of fishing in that general area - we sampled river trout fishing which doesn't really compare to ours and barbel which are meant to come to fly but didn't.
Magnus
PS - does 'The Girlfriend' get a say in where you go? or the type of holiday?