I had a pair of Adidas thong sandals for a few years that were wonderful, soft, pliable, didn't slide on the foot while walking, but eventually they wore out so I shopped for a new pair.  Of course that style is no longer made.  I bought these sandals, which are comfortable and padded nicely, but they slide on the foot while walking.  The strap is somewhat irritating.  They flap while walking, which the old ones did not do - they curled with the foot.  As for size, I bought a size 7, though I usually wear an 8 in regular shoes, and the 7 fits well, so I guess they run a bit large.  All in all, I think it's best to buy shoes where they can be tried on.  I'm still looking for the ideal thong sandal.  This isn't it, probably not worth the price really, so I'll keep them and wear them around the house for indoor slippers.