I have some thongs that are very comfy and others that are indeed devices of torture (need to just toss 'em out!) They really do vary a lot, depending on fabric, fit, cut, etc. I bought most of mine on sale from Victoria's Secret so wasn't always sure which ones would work for me when I purchased them. I wear them whenever I wear pants that will show VPL, but some pants don't, and then I'm always happy to wear regular undies.
Emily
2011 Jamis Dakar XC "Toto" - Selle Italia Ldy Gel Flow
2007 Trek Pilot 5.0 WSD "Gloria" - Selle Italia Diva Gel Flow
2004 Bike Friday Petite Pocket Crusoe - Selle Italia Diva Gel Flow