@thisisnotadrill That is a great suggestion that I just did last night and it saved me $20 and maybe my marriage! I cut out both the rectangular, the quadrilateral as well as the triangle shelf and the other corner shelf that is triangular but more squared off. Everything will fit on two of them. I almost ordered the quadrilateral one but the wife prefered the shelf-E with corner/squared off one. Plus, I am putting one of the triangle corner shelves at the first grout line 24" high for her to put her foot on to help shave her legs.

I had a similar dilemma, and ended up choosing two of the "Narrow Combo Niches" from the Noble Company. They're not installed yet, so I don't have any pictures. I wanted my storage to be as unobtrusive as possible, but had previously been unimpressed with too-small niches that had potential moisture issues. When I found these, I was very excited since they make a watertight installation very straightforward and the two levels neatly accomodate soap, razors, etc. The niches were 56.75 each online, so it is less than some options but not as cheap as the Bed Bath & Beyond caddy. I'm also going to re-bottle my shampoos, facewash, etc. into plain, narrow plastic bottles. You can fit 2-3 of these bottles in the space of one normal shampoo bottle, and they look much nicer. For my brush and pouf, I plan use a natural sponge and a cute wooden brush that can hang on little suction cup hooks. Hopefully, this will look spa-like and not junky. I'll have to replace the natural sponges more often but I think they're nicer on my skin and more attractive than the plastic ones. Here is a link that might be useful: Noble Niches

I like both niches and having a ledge for shaving. But the niches do need to be up far enough and out of the way of shower spray to keep them from getting gunky. I've found that behind the shower spray doesn't cut it and I hate the corner things that aren't really 'niches'. Had one in a former shower. Also they need to be big enough to put most things actually in them, including tall bottles, with shorter things and razors on an upper shelf within the niche. The lower ledge for shaving should also be out of the way and not so big as to obstruct a person standing under the shower. Good examples, Eureka.

Corner tile shelves blend right in and are not too intrusive. This works best if your tiles are the same through the entire thickness, rather than a glazed ceramic. You could use a complimentary stone. I've attached a link - scroll down to see some pics. Or you could google "tile corner shelf" images to see more. Here is a link that might be useful: Corner tile shelves