Option 1 is more pleasing visually.

Having an accent element relate in proportion to another element being used in the design is the best choice. So, a 12" wide strip with a 12"x24" tile. Or, a 24" wide strip, with a wide niche in in. 12" is narrow for a niche. I am presuming that you are doing a niche?

How are you trimming out the edges on this? We used bullnose below, but we could have used Schluter. The HO wanted the narrow strip to accent the narrowness of the accent tile here.

What waterproofing system is being used? This also used Schluter Kerdi.

Blue Gray Inspired Hall Bath · More Info

Thanks for the replies!

Good point about keeping things in proportion with a 12" accent - looks like three tile wide mosaic might be the way to go. I like both options, but was a bit worried that three tile wide looks a bit chunky. But keeping things in proportion seems like a good idea.

Edges will be trimmed with those aluminium edges.

There will be a niche, but due to the constraints of our townhouse (back wall of tub is a shared wall with next door and the left wall is an exterior wall), the niche will be on the right wall (where the fixtures are) and will be two smaller vertically stacked niches (I kind of prefer the niche to be less visible anyway, as then people won't see all my bottles :p).

So the back tub wall will be flat, without any disruptions to the vertical accent. The door to the bathroom is on the right side (when looking at the tub) at the far end, so when you enter, you sort of see more of the left side first than the right - so I thought I'd put the vertical stripe off-centre to the left.

RE waterproofing - my contractor has used DenShield with mesh tape over seams/joints/edges/nails and then RedGuard on top of that

Paint the edges to match the tile those aluminum edges look like commercial bathrooms. Most tiles can have their edges polished and color matched paint applied. Remember common latex paint holds up in exterior applications no problem. Polishing the eyes produces a smooth finish and if you bring the tile to Depot for a color match you will not notice it isn't intended to be a bullnose.

Thanks everyone for the feedback. Wannabath thanks for the suggestion, however I actually quite like the aluminium edges - but I think my tastes go towards that sort of style. If anyone is interested in some quick phone pics, the tile is up now and I really like the look of it, glad I went with the three tile mosaic stripe:

Striking tile layout!

Option 1 was my choice before scrolling, and DAMN that looks good!