I took the same approach when choosing my wood look tile grout color and picked a medium shade of brown from my tile: Just dark enough to show the grout line but not so dark that my eye is drawn to the tile shape.

White to match the field on walls. Or the PALEST gray. Palest gray on shower floor. Just note that any contrasted grout, especially on white subway, requires absolute perfection in install. Depends the look you want, but white subway is classic, and so is a match in grout. also........NON busy.

use the grout color of the floor tile . Darker caramel it appears. ....almost a light brown....can tilt it a little grayish as well. Gives you a tie in with something.

for what it's worth, I think the bone looks better. The white is too bright against the tile color. That said, their grout job was horrible on that first pic. the grout is patchy and somewhat low. when you have grout that sits that far below the tile surface, you're going to catch a lot more dirt and grime in the 'divots'. so yes, the sooner they scape it out (2/3rd's is fine) the sooner they can go back over it w/the white. just make sure they do a good job w/the clean up