HOTMAMA,
I've stayed at both the Riu Cancun, and the Gran Melia. I've also stayed at the iberostar. It just depends on what your looking for? Which Iberostar property where you looking at?
Okay, now for the advice. The Riu Cancun and the Gran Melia are two different hotels. They both are nice, but offer different things at them.
Riu Cancun: Very, very nice hotel. The rooms are great!! nice big bathroom with double sink. Nice mini bar in the room, with beer, water, soda, vodka, gin, tiquila, rum. It has a in room safe, and every room is an ocean view room!!! The service there was GREAT!!! I never had any problems getting what I asked for. Everyone there is friendly, and the check in and out, was a breeze!!! The only dowside that I would say this hotel has, is it's pool area isn't that big, but still comfortable enough to lay out, drink ect. Also, this hotel is within walking distence to the bars, clubs, shopping, and eating. That way you don't have to take the bus. But, the bus ride is only 50 cents.
Gran Melia: Very nice hotel, okay rooms. Service is so so. You have to sign for everything that you get. Food, drinks, ect. This becomes a pain in the butt. When your at the swim up bar, and your all wet, you have to sing for your drinks. There are some people there that are all-inclusive, and some people there that have time shares, and then just others that are just paying for the room. So it's not like an all-inclusive hotel in that sense. The food there is good, not the best, but not the worst either. The drinks are okay, not the best, but not the worst. One good thing, you can order food at the swim up bar, and they have servers that walk around taking your orders. The fied shrimp, pizza and burgers at the pool area are GREAT!!! I had them everyday. Also the cocktail shrimp!! The service wasn't all that great. If you don't tip them, they usually don't wait on you as much. There are other people there that aren't all-inclusive that is giving tips everytime they get something, then tend to wait on them a lot!!! The pool area there is GREAT!! it's big!!! and the beach is really nice!!!
I hope that this helps you out some. Feel free to ask me any questions that you want answerd. I will do my best to help you out. I've been to Cancun 21 times now, so I do know a few things. lol
My email addy is modelme2000@yahoo.com
Chad