I wish we could blame Jonathan Adler whose life-size fantasy beach house for Barbie in Malibu garnered plenty of press (parts of which were later relocated to the Palms Hotel in Vegas), but the first Barbie-themed hotel room seems to have sprouted its girly, pink head back in 2004.
Since then they've been commissioned, at least for short periods of time, by hotels around the world to, ostensibly, draw in parents of Barbie-loving kids or, perhaps, adult fans. The unifying design element is definitely pink, and lots of it. Some interpretations are more modern and mature, while others are more frilly and girlish.
Hotels in Toronto, Peru, South Korea, Spain and others have also hosted Barbie-themed rooms and suites. I've yet to discover any Ken-themed rooms. Hmmnnn...
(Images: as linked)