Place the curtain rod as high as you can to the ceiling. Ceiling height makes the room bigger. There are 96 and longer shower curtain liners. You can use two actual curtain panels in a natural fabric, like from Ikea.

There's a lot to be said for being able to use a standard 72" curtain, so you can swap curtains as you wish over the years. I would hang the rod to plan for that, and for the curtain to come just to the floor without puddling. A 6'-high(and a smidge) rod will also allow you to reach easily to hang a towel over it or similar.

For keeping water in: the curtain will not actually act as a seal, so it doesn't need to perfectly meet the floor, but I would not allow a large gap at the bottom. I would definitely use a weighted curtain. Water containment will depend mostly on correct slope of the floor and the orientation and strength of the spray.

We did a custom glass door in our curbless shower. Aesthetically I think a cleaner look if your budget allows.

Bump

We have a curbless walk-in shower (bathroom is totally open). How high should the shower curtain rod be? I’m not clear if the shower curtain should touch the floor in this instance (I’d think so, so water doesn’t flood the bathroom). If it does touch the floor, it shouldn’t drag. If we use a 78” high curtain, the rod either needs to be super high or the curtain drags a lot. If we use a 72” high curtain it seems the rod would be too low for the curtain to graze the floor. Otherwise the curtain is too high off the floor. So what do we do? How high should the rod be and how long of a curtain?