If you are already booked at Ramon's why not dive with them too. They are as qualified as any other place. As everyone who reads this board knows, I always promote Ched. However, since you are newly certified, will be staying right there and can spend some time hanging out at the dive shop, I suggest you seriously consider doing this.
You can learn a lot this way, they can learn a lot about you and after each dive/day, adjustments can be made.
I know you will be back to San Pedro for more diving (it's kind of addicting). So use this trip as a base, walk around, get to know people but don't worry about getting the best "DEAL" on this trip.
One last tip: I would urge you to not go off on your own, follow the dive master. S/he will show you the best there is where you are.
HOWEVER, follow does not mean "CLING" The biggest mistake new divers make (and I did too) is staying to bunched up, kicking each other, stirring up the bottom, etc. Ten to 20 feet to one side or behind is still following.