A tropical patio needs a centerpiece. If you have a swimming pool or yard pond, you already have a centerpiece but if you don't consider one of these options:
Fire - Yes, I know fire brings to mind heat and most tropical locations don't need help in this arena. However, think about a bonfire on the beach at night, or cooking over an open flame. Fire really does have its' place in a tropical theme.
If you don't have or can't build an outdoor fire place, consider a fire pit. They are a wonderful way to still have a focal point or centerpiece. Their portability makes them even more attractive an option. Move it around until you find just the right location for guests to enjoy their ambiance on a cool spring, summer or fall evening.
Another centerpiece idea for a tropical patio is plants. Build a small potted garden that can be situated in a way that all seating areas get to enjoy the view of lush vegetation. And, a potted garden means you can bring it indoors for the winter.
Try arranging different sizes and shapes of pots together. Add a low bench or table as a riser for some pots. This will add height and dimension to your vignette. Use pots in the color scheme you have chosen to add a pop that is sure not to be missed.