I booked a six night stay at the London Regent's Park Marriott on the internet for a decent, yet unspectacular rate of $225/night.
I cancelled the day I was supposed to arrive, and Marriott has charged my for the full six nights. I got absolutely no service for this; only the chance to play around on the Marriott web site. A decent cancellation policy would be to charge for one night and provide credit for the remainder.
Marriott will not refund or allow me to rebook. This is the worst policy I have heard of with any hotel chain. Do not book with a Marriott when you have so many other choices. It's just not worth it.
Also, their complaint channels are anonymous and faceless. It's hard to get a full name out of anyone you might complain to. They all run and hide. It's very unprofessional.