Over here we have Boost Juice which is like a smoothie bar. Anyway, my fav is Green Tea Mango. It's Yoghurt with Mango and green tea - amazing!

If I make a smoothie at home with yoghurt I like to use the natural kind with no flavouring - I find it adds a sweetness and I do like that tang of natural yoghurt. Anything with strawberries is good.