I use the vanilla whey. You can't taste it in any smoothie.
I found small tubs of it at WalMart. They had strawberry, vanilla and chocolate. Many whey sources sell in big jugs...which may be cost prohibitive for some people. I don't know if WalMart still sells it that way, as I haven't bought any for over a year now.

We liked our smoothies thick like shakes. So I used yogurt too.
I never used OJ, but did use pineapple juice to thin them some.
I also did them in stages, to help with mixing. I put the thickest item (banana) in first, then added the other things that were thinnner. I have a hand held wand and not a blender. It probably doesn't matter with a blender, or food processor as much.

We had alot of fun with them. And the smoothies were really delicious.