We've been to Cancun and Playa a couple of times each and only had a problem on our last trip in December to Playa. I'm not going to tell you what boutique hotel it is, because I still like the hotel and it tends to have a very good reputation. We just bought a video camera to take video's of Playa so we could show people the place we're always bragging about. We lock everything up in our safe, passports, money, Ipod, wallets, and video camera, & digital cameras, but one night we forgot to put the video camera back in the safe after using it all day and we went for dinner at 6:30 and came back at 10:00, finding our door sitting ajar. We looked around the room and in the safe and everything looked fine, so we thought we were lucky. The next morning as we were getting ready, I went to put on my Ray Ban sunglasses - gone. My husband had brought two pairs of sunglasses, one he always wore and the Oakley's that he's had for years and hadn't worn down there yet - gone. Then we realized we forgot to put the video camera in the safe and it was gone as well.
So the short of this story is, everything that we did lock up in the safe was fine, anything that's out, you take a risk of it going missing.
I will still go to Playa, but I will only stay at a place that has a safe in the room and a deadbolt on the door.