Thongs are VERY obvious if you're wearing yoga pants or those bum crunching legging things (whatever they're called)
But as with occasionally visible bra straps i think - "meh! women wear underwear get over it"
From a VPL POV the seamless ones are best, and aesthetically much better.
I'm #TeamBigPants - have been forever. i also like calvin klein style boxer things for women. Both my DDs like big pants, they go for nicer looking lace edged. I just go for price/quality.