I have some from Costco. They are past the hips, simple solid colored tanks. Very soft. I bought them for pregnancy, loved them so much I bought more in my regular size.
I am loving the Tamis from old navy. They are smooth, long, come in tons of colors and not super expensive. I have them in 3 colors with another 3 ordered.
Re: S/o work wardrobe
Most of mine are from Aeropostale and Target. I like the ones with the built in "bra" and also long, and they both work well.