I think even supposedly "random" designs have a certain symmetry and the way you have yours laid out doesn't have that symmetry.

For example - Versailles pattern tile. Its not random but can appear that way versus random mosaics that achieve their consistency by sheer number of tiles.

I think your idea for accent strips that are both two tiles wide and three tiles wide, and both on and off center, it would be difficult to achieve that symmetrical randomness that would be required for it to look good. So failing that, a more traditional accent - horizontal or vertical stripe, for example, would make more sense.

I cant really find a good photo to illustrate the concept but you can see it here - this person does a pretty good job with symmetrical randomness in the placement of these 1 inch tiles. I think your tiles are too big, and the area too small, for you to achieve the look without a whole lot of fussing about the placements.

Good luck!

PS Oh and who cares what happens to the tile when you pass on to your reward! Enjoy now. In 20 or 30 years someone will want to redo the bathroom tile anyway regardless of which you choose!

[houzz=]