There was a record count this morning on the high tide of 9 purple sandpipers at Battery Point. Park at the Lido on Esplanade road, walk up the steps onto the headland and go down towards the lighthouse but look down to your right before you get there. They congregate on the northern side of the rocky promontory on which the light house sits and tend to be pretty amenable to viewing and photography as long as you remain fairly still. If you try to find them at low tide, you will have a much larger area to search so good luck to you!
The beach by the esplanade has lots of rock pipts and turnstones so there are plenty of good photo opportunities.