I came to Hyatt from Hilton several years ago and have been very happy with the decision (if you can live with fewer properties). Hyatt customer service is top notch. I think you may have had a stretch of bad luck. I've never had a problem with bed choices - in fact that is one of the diamond guarantees.

I would say don't give up hope. It's a different culture and things work a bit differently than Hilton.