That is a hard one with those tiles. I would have to think if you did a white, it would kind of work with the colour of your tiles. At the end of the day, they do need to be replaces, but as you said, due to budgeting reasons, you cannot, I can pass on this photo of a nice bathroom with those tiles for you though for inspiration... : )

I work in tiles and a trick you can use is to lay the tile horizontally on the 'narrow wall'. This gives an optical illusion that the room is wider. These tiles at around $50 each can certainly add up so a wise use would be to use as high impact. In the ensuite use them behind the bath for the whole wall. Use white wall tiles for the rest of the walls. If you want to add more colour, tile the spa box in an colour tile that exactly matches the blue or grey from the pattern tile, use a matching grey tile on the floor instead of white. Or use the pattern tile behind the spar, make the rest of the room white and add a matching grey vanity. It's a lovely tile but may become a bit gaudy if you have a bit here there and every where. Again with the main you will probably not get an exact match with the outer room timber floor and it could look like you tried to match it and couldn't better to go for a complete contrast. Use the same tricks as the spa bathroom and don't forget matching blue towels for a bit o colour. Hope this helps.

It can either look really dramatic or too dark, depending on the size of the room as well as your other components. I've attached a couple of images of our work using dark tiles, the smaller bathroom we have surrounded the bath with dark tiles but then balance it with an extra large mirror to bounce the light around the room. The larger bathroom we have taken the floor colour way onto the wall but used a different texture on the walls for drama. Hopefully this gives you more of an idea but you shouldn't to nervous of the room being dark, it's where you can create a contrast as well as textures. Look forward to seeing what you go with in the end.

Attach are photos. I have been told by 3 different bathroom / plumbing co's it is not mould. They have scraped out some grout, put new grout in & the dark stain has come through again. The builders warranty expired Nov 2015. The builder passed away about a year ago but his wife is still alive & she was co-builder / co-vendor. But, as I'm out of warranty not sure if I have a leg to stand on. It has been suggested that the experts scrape out all the grout, silicon the bit where the stains are & re-grout & maybe the rusty nail stain doesn't break through the silicon / new grout. Can the wrong nails be used in wet rooms that has therefore rusted? Is there normally special nails for wet rooms? Has anyone heard of a 10 year builders warranty - standards & tolerances - for major defects; possibly like this? Thank You. It's very annoying I must say.