I can't help but picture orange with this blue. Or a saturated blue and white. A textured all white curtain would look great as well. In no particular order, here are links to a few colourful patterned ones I found: Peaches - orange pink and green - Urban Outfitters Blue and white - Urban Outfitters Flamingo - Anthropologie Orange Contemporary - Rachael Taylor - Wayfair Medallion - Blue and White - Target Navy & white - Wayfair (might be too dark) Orange and white Ikat - Wayfair Lime? (Doesn't look lime on my screen) - Red Barrel Studio - Wayfair Moroccan Orange - Wayfair I think you can have a lot of fun with your shower curtain. So many colours look good with this blue. The trick might be to match the colour intensity.

I don't know if "I've seen much worse" is at all helpful, but, I have. With your tile at least it creates a sort of rhythm rather than looking like a "crack" or "seam" between tiles. I think the light grout does emphasize it a bit, and honestly light grout is usually a pretty poor choice for a floor, especially a shower floor, because it will stain and discolor. Even with good maintenance.

Been used for centuries. Use non-acidic cleaners like MB Stone Care. Take the easy precautions (true for any shower surface) and ensure proper ventilation (and use it), quick squeegee and wipe with micro-fiber towel after use. Of course the most important factor for longevity is not the tile or stone on the surface, but how the shower was built (methods and materials). And yes, pay attention to the quality of the marble. It does make a difference. Like anything else, you will pay more for quality.

Really? -because I wasn't following. Yes, the shower floor is above the bathroom floor, but it slopes down on all sides, toward the drain in the center. Does this show it any differently? Or is there still a concern? In other news, I really hate that I didn't nab that illustration that @Greg GN Builders. offered up before it disappeared, but I think I've got it - and it sounds like the same as everyone else has suggested. Thank you all!