I stayed at Ramon’s on San Pedro about 3 years ago, around the same time mid-May. (http://ramons.com/) And I would highly recommend it. Our experience was that the dive boats were small, so we never had more than four divers on a boat which I loved! We usually don’t go with a guide, but because there were only a few of us we followed him and he took us through some great caves and to some good spots. So overall great experience with the dive team there. The hotel is pretty nice, the showers are small and there is no tv if you stay in a standard room. But overall the atmosphere is really cool with small thatch roof cottages for rooms. Location is good for walking into town to restaurants and such. Good luck, let me know if you have any more questions.