Great thread topic. All my peeves are about hotel design...

** Incomprehensible thermostats / HVAC controls.

** Mystery temp / flow controls on the shower.

** Insoluble alarm clock controls. I like the Hilton standard alarm clock / radio, I've figured it out and it's the only one I try to use any more.

** Overdesigned shampoo / conditioner / lotion mini-bottles that defy opening when your hands are wet and slippery. Caps should be ridged so you can get a purchase! And thick, viscous lotions can be impossible to extract from slim, small-necked bottles.

** Stylish lamps that you can't figure out how to turn on or off. I was just in a London hotel for three nights; spent two of them reading in semi-darkness before I figured out that my stupid bedside lamp had two different bulbs and switches, one almost completely concealed from view by its chic design.

** Weird light switch placement or function. Wall switches control lamps or lights that you don't expect... or not. I hate havng to hunt by feel for the bathroom light toggle in the middle of the night.

In short a hotel room, like a rental car, is no place for mysterious design that has to be deciphered.