I've used BeoLab 3500s in the bathrooms for over 15 years without any problems. I like having the Essence Wall Remote for control since it's not connected to the electricity. I can even reach from the shower and control the volume, etc.

I'm using a Beoplay M5 that sits on the bathroom counter.  I have a Beosound Essence Remote mounted on the wall lust outside the shower door so I can control the M5 while in the shower.  :)  

I have a M3 on my bathroom counter, but will mount it on the wall in an upcoming remodel. 

I’ve got a pair of BeoVox 1 (mounted in the hidden extra wooden boxes for better sound) in the ceiling. Looks really nice, but sometimes I look at the wall and think a BL 3500 would have been great there. As long as you don’t place it right over the shower there should be no problems with a BL 2000 or BL 3500.

I use a Beosound 2. 

The M3 is a good natural choice. In my case, I use my P6 as a bathroom speaker. I use it via Bluetooth connected to my phone. It auto connects and it’s splash proof. My bathroom has an inbuilt usb charger so that helps as well. For a permanent solution, I’d pick an M3.

Ah. I was using my Beosound 1 but then got worried that the humidity might effect it. Since I have it on the dock, charging in the bathroom was good and it looks good as well. I switched it for the P6.