Hi Lindsay if you think its "bitter" (i think you mean tangy/tart) maybe you can try to find Chobani Brand of Fat free greek yogurt. It's pretty bland on the scale of plain yogurts as far as I'm concerned. I happen to love the tang of true yogurt myself
I have found wonderful extracts/aromas to make my plain yogurt more interesting.
Coconut extract (my favorite)
Imitation Rum (added with sprinkes of cinnamon/ginger)
Sprinkle of Cardamom (it's strong like ginger)
I could go on...extracts can be really helpful and they don't add dreaded calories.
All of these I add a sprinkle of stevia/splenda too to sweeten.