H.S.
I would recomend not going there. We went 2 years ago. A few months after Rita and it is just a hassle, or extremely expensive to take cabs, to get around outside of the resorts. If you have no desire to leave the resort, then you may enjoy it. They just had another hurricane go through there.
I would HIGHLY recommend Puerto Vallarta though. It is a really fun place and easy to get around.
If you do go to RM, stay in a highly rated resort, so that you have the most to do since you'll probably want to spend most of your time there.
H.