I wear the Frankie and Essential Tank under my dresses when travelling, then use them as pyjamas at night. Makes for less weight to lug through an airport or train station.
Not see-through so I also wear it for yoga or hiking and have not had a problem with the legs rolling up or bunching. The wee waist pocket is just right for a house key, lip balm or bit of cash.
I am between a Medium and Large in bottoms so got the Medium since Wooland products tend to relax and conform to my shape.