Finally found underwear that doesn't show!
I hate thongs, and could never find underwear that didn't show through some of my tighter pants. Now I've found them! They are Maidenform Tanga, style #40381. I was doubtful at first, since they cut across the middle of your rear, but they really are great. Unfortunately they only come in sizes 5,6 & 7, but if you fit those, try them!
Here is a link that might be useful: Maidenform Tanga