Of the four, I've only had the stainless steel shower caddy. It gets soap scummy and it's difficult to keep clean. I'd go with one of the other options. :)

If I were you I will put in a niche, just make sure you measure the height of your shampoo bottles so, it fits into the opening. Goodluck!

Niches away from the shower head work for me. I have tried the others and prefer the ease of accessing and cleaning the shower niche as shown in your photo 4.

I think a shower niche will work the best for you. The shower is not that large so it is nice to hide the shampoo bottles. I have a couple pictures on my page that may help you.
http://www.houzz.com/pro/tiletom/__public

Thank you, all! Niche it is (niches, they are?). Now, two more questions:

1. For both bathrooms (shower one and tub one), should I put the niche on the wall OPPOSITE the shower head? Or on the side adjacent to it?

2. For the one in the bathroom with the tub, would a small niche look funny centered in the middle of the tub wall? Or should I go large with it? For the record, that bathroom will be travertine, with that back wall darker than the rest of the room (an accent wall).

Thanks!!!

In my last two bathroom remodels, I used a glass shelf and placed it on the wall opposite the shower head. I really like this option because they are easy to clean, hold several bottles, and are transparent (so they don't impede the space or design).

Thank you so much. I'd never thought about what mcs0430 said re not liking to see the bottles et al., but now that I DO think of it, I'll probably decide to keep them out of immediate view. Glass shelf also seems like a good idea, though I'd have to place it high enough in the bathtub area to prevent my hitting it when sitting down/standing.