Oh, dear, a tricky question indeed. Let's see......it depends on what your father likes and what he needs, but here are a few ideas.
1) If he's into gadgets, consider getting him the latest smartwatch, a new smartphone or tablet, or a high-tech camera.
2) If he's into sports, consider getting him a gift certificate for his favorite sport store or a new piece of sports equipment.
3) If he's into music, consider getting him a new CD or concert tickets to a band he likes.
4) If he's into reading, consider getting him a new book