Dusk is great for drum circles and grilled sweets. This is a great time to light planted tiki torches to keeps bugs away and to highlight the impending sunset. Toss some fruit on the grill for a sweet surprise dessert. Watermelon, peaches, strawberries are all awesome on the grill, but any fruit (or avocado!) works great.
Have guests BYO percussion instruments, and purchase a few of your own to add to your party closet. I like tambourines, rhythm bongos, and percussion blocks.