Underwear that doesn't give you a wedgie?

I can't seem to find any underwear that doesn't ride up my butt when I walk. It's worst when I wear jeans, but not so bad with skirts and dresses.

I've tried Target, Bonds, Kmart, bikini style, midi style and full briefs. I haven't tried Boody.

I don't know if I just have a large butt to hip/waist ratio, I usually size up and the fit feels good when I'm standing still but as soon as I walk around - immediate wedgie! It feels like the elastic around the butt almost isn't firm enough?

So does anyone have recommendations for underwear with good butt coverage and that actually stays in place?!

EDIT: I've had so many great responses to this post in a short space of time, thank you everyone. I'm planning to do some detailed research, create a shortlist and then purchase 1 of every option and trial them all before deciding on a winner to stock up on. Maybe I'll do a detailed update/review post once I've tried them all.