the command hooks are excellent.
I got an over the door metal coat hook thing at target and put it over the bathroom door. our sink is outside the bathroom and we use it for towels mostly.
Inside the door I put the TP holder - don't want to put wet towels over it.
Put a regular towl bar above the toilet on the wall - used the expanding anchors (cheap, plastic) that came with the towel bar (and TP holder same deal).
Then we got a spring loaded shower pole/shelf like this Tension Bathroom Shower Caddy ? White ? Walmart.com
and it works great - stays put in the back corner of the tub/shower.