I don't like when my lines show. I have to impress my horse you know, I wouldn't want him to think that.....I wear underwear!
I don't know why it bothers me but it does. I don't care when the other ladies at my barn let them show but I try my best to keep things seamless.
I found some underwear that's SUPER thin (pretty much see though but oh well) and has lace at the edges and it still shows a tiny little bit if you look hard but just barely. Here I just found them: http://www.kmart.com/shc/s/search_10...the+loom&vName
I've tried riding in a thong and...it's just not for me. I'm just not into them anyway. I'm more about comfort. But if you don't mind riding in a thong or commando it's definitely good for keeping those lines away!
If you're brave enough to go commando they have these patch things: COMMANDOS - Welcome
I saw them recommended in a riding magazine once, actually..haha