There are MANY things to do in Tahiti and a lot to see and take pictures of. Should you embark on a circle island trip (of around 70 miles), some of the must see things would include:
All nautical activities: surfing, scuba diving, snorkeling (most resorts will provide you with the equipment for free), canyoning, stingray and shark feedings, water sports, deep sea fishing, kitesurfing...you name it.
You also have the possibility of hiking, 4WD safari, golf...
Deep sea fishing has been curtailed on Tahiti and is difficult to find.
Diving: get a reputable dive company, our experience was that those with the far out websites were a bit low on ethics and safety, not well prepared, and did not go far past the marina.