You can get Perpetuem unflavored, just have to buy the 16 servings packet. I haven't tried it as like I said I'm a big fan of the Latte flavor. I never drink straight coffee either, it's too strong for me so I get a mocha or something along those lines, I would say that the caffe latte is more like that then coffee it's not bitter at all.

Haven't tried the Sustained Energy yet.

Hope you find what you are looking for though!