I usually just bung a bunch of complimentary fruit in a blender with a bit of yogurt and/or juice and/or coconut water when I make smoothies. It works reasonably well. Pineapple and coconut water on its own actually makes a really nice smoothie. However, Cook's Country published some actual smoothie recipes in their latest issue and I have to say, I'm really impressed with the results. Their version uses a banana-honey base and quite a bit more yogurt than I'd normally put, but it makes for an extremely creamy, mellow smoothie. It doesn't taste as fruity or acidic as what I normally make. It's a bit more subdued and more filling as well which is great for breakfast smoothies.
From Cook's Country April/May 2016
1 Tbsp. honey
2 Tbsp. almond butter
tiny sprinkle of salt (~1/16 tsp.)
1 c. frozen cherries
1/2 c. plain yogurt (original recipe recommends whole milk yogurt; I used 2% because that was the only variety available in lactose-free)
2 Tbsp. milk (again recipe recommends whole milk; I used LF 2%)
1. Puree banana, honey, almond butter, and salt together until smooth.
2. Add remaining ingredients. Puree until smooth, scraping down sides as needed. Enjoy!