Personal preference - they both look great! But the black grout is more of a statement (which i love!)

Hi Sue, I think it would look amazing if you used some tiles with a bit of texture. The wood look tiles that are popular at the moment would be an example. If you chose a colour that toned in with your floor you would get a really nice cohesive look but with a bit of interest. I've attached a photo of a recent design of mine as an example. Just a suggestion!

My suggestion is first talk to the builder to see what instructions he gave the tiler as i'm sure he doesn't want a dissatisfied client. Most tilers will check with the builder before grouting especially when a colour is not specified in a contract. I would then ask if the grout could be replaced, from the looks of it it will only be a couple of hours work. There is nothing worse than having to look at something you are not happy with. I would not use the paint product as it will alway look like it is covering a mistake. White will look better. Make sure the mixer body is waterproofed or you will have a leak in your wall, the membrane should lap onto the body from the wall if it is done well. All the best.

I think she may have been referring to what is called a "French Pattern" which looks like a random mixture of square and rectangle tiles, often in travertine. However while it looks random it is actually carefully planned, and the tiles are made to a consistent thickness. It also depends on the type of tile that you are using. Many traditionally hand-made ceramic tiles have a natural variation, which adds to their appeal and visual interest. Other types of tiles, such as your porcelains are much squarer, flatter and almost identical. I would suggest that you go with your your choice of grid pattern, as laying a random pattern has too many risks (plus your tiler will hate you and charge lots extra). Be very careful about the selection of your tiles depending on your preference for a rustic more organic look, or a hard-edged architectural look. Make sure that the surface that you are tiling to has been properly prepared and is flat, smooth and true, as your tiler will not be able to correct imperfections if you have a bad wall. Best of luck, Dr Retro of Dr Retro House Calls