Another thought... I don't know what you are like with textures... But there is a place in Aussie called 'Boost Juice' and they make a whole variety of natural juices and smoothies and shakes etc.

One shake that they do is called 'Breakie to GoGo' and it has coarsely ground toasted muesli in it. I thought that sounded strange, but one of my friends absolutely swears by it as their tastiest smoothie. Theirs contains bananas, but there is no reason why you can't substitute banana for something you like.

I was thinking that if you didn't mind the texture (or liked the texture, even) then you could get a few nuts in your shake which would add even more protein to it and make it into more of a meal.

Here is their menu which might be a little inspiring for ideas (the TD4 is just their brand of low fat frozen yoghurt)

http://www.boostjuicebars.com/#products/our-menu