We have 2 niches in our new mbr shower and I like having 2. DH keeps his shampoo and conditioner in his all the time, but I only put my stuff in there when I'm going to use it, as I don't shampoo every day. Mine gets damp with every shower, but only really what I would call ''wet'' if I am using the niche. Since we're still in the honeymoon stage with our shower, I do dry it every time after I use it, but I probably really don't need to do that.
Here's a pic:

For me, it was more important that I have enough space for my stuff than whether it looked crowded. I want enough space that I can easily grab what I need without worrying about knocking things off the shelf or having to shimmy it into place. For us, that meant two niches.

There's just me in my house and I have one niche and it holds everything I need. If I want to use a different shampoo I get it out of the drawer and return it. I don't have everything I could ever hope to use sitting there.

My niche is at the opposite end of the tub alcove from my spray. The water doesn't reach it under normal use. The bottom drains and there's never accumulated water sitting there.

If you don't mind what it looks like, put in as many niches as you need. Everything will still look like shampoo bottles and razors whether it's in a niche or sitting on the floor.

Our shower has two niches -- one for hubs stuff and one for mine. Love them!

What I normally do is make a larger niche with two shelves, made from the same stone as the vanity top in the bathroom.

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If that's not enough, no one says you have to stop at two shelves!!

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To me, it's not the number of niches but what is in them that contributes to the "cluttery" look.

For example, these two are huge with lots of items, but they are color coordinated and a soothing palette.

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[Traditional Bathroom[(https://www.houzz.com/photos/traditional-bathroom-ideas-phbr1-bp~t_712~s_2107) by Montclair Kitchen & Bath Designers Tracey Stephens Interior Design Inc

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[Beach Style Bathroom[(https://www.houzz.com/photos/beach-style-bathroom-ideas-phbr1-bp~t_712~s_2110) by Los Angeles Architects & Building Designers Evens Architects

The mutliple niches here look nice too:

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[Traditional Bathroom[(https://www.houzz.com/photos/traditional-bathroom-ideas-phbr1-bp~t_712~s_2107) by Tempe Design-Build Firms Holtzman Home Improvement LLC

Whereas this one is overflowing to the caddy and a mishmash of color.

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[Contemporary Bathroom[(https://www.houzz.com/photos/contemporary-bathroom-ideas-phbr1-bp~t_712~s_2103) by Boston Architects & Building Designers Helios Design Group

And this one is very spartan but definitely not as "pretty".

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[Craftsman Bathroom[(https://www.houzz.com/photos/craftsman-bathroom-ideas-phbr1-bp~t_712~s_2116) by Seabrook Kitchen & Bath Designers Lowe's of Seabrook, NH

Thanks everyone for responses. Looks like two niches is favored. Nobody appeared to have sitting water probs. I tried to use pretty bottles to avoid the junkie look but some products such as rinse are too thick to transfer successfully, so I've given up on that. Maybe I can place niche(s) low enough and on opposite side of plumbing and get needed storage but out of sight.

The surfaces in the niche definitely need to be slightly tilted to encourage water run-off. A good tiler will know to do that automatically.

That makes sense . I'm worried no more

I tend to agree that two is the way to go if you can swing it. In my case below I made the niches the size of one full tile.

Note:

When this photo was taken, I was still not finished with the bathroom reno as you can see Brushed Nickel and Tuscan Bronze trim together as well as the wires for led lighting in the niches which I never finished. .

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Both my master shower and the hall bath have the niche like the Craftsman Bathroom photo. The top one is for the tall stuff and the 4 inch tall one is for your soap, jar of sugar scrub, loofa, razor, etc. But it is personal preference.

Ok, I have a niche. My niche is always wet, and I have to wipe it down after every shower just like the rest of the shower. I squeegy and wipe the caulking down with a microfiber towel. My shelf is beautiful but I don't keep much in there because I have to move it all around to wipe it down. Linelle's niche is the answer, have it mounted at the back end of the area. Some of the pictures posted above show larger showers where the niches are probably out of the spray zone. My shower is 36x60. The niche is on the side wall. The far end is always dry while the front end is sopping wet.

This is an in process, nearly done, picture of my shower.

Darn the above image was large until I went in to edit some text then when I resubmitted the image turned small with a blowup available when the cursor is placed on the image.

I am going to add another picture and not edit, and see if it stays large:

Edit to say that after leaving the page and returning they are both large again.

Here is a good selection of shower niche design ideas.

http://www.houzz.com/ideabooks/42722/thumbs/shower-niches-how-many-and-where-to-place-them

We are replacing tile around our tub and are doing 1 niche. The current bathroom had none, which I hated. The shampoo bottles which were placed on the side of the tub were constantly falling in the tub or out on the floor. Our niche will be about 12 x 23? We ordered a preformed one, to make it easier. The bottom edge is sloped so hopefully water will drain and not sit there.