On my recent trip I traveled from Franz Joseph in the south to Karamea in the north.
The sea was rough and the beaches often shallow. The beach I most liked the look of along the coast was called gentle annie about 20 minutes north of Westport. It has a nice river mouth and a campground close to the water.
North of Karamera, about 40 minutes along the hephy track this was a few nice rocky points also.