Hi,
Riu Caribe is pretty much next to the giant Mexican flag if that answers your question.
Stayed there last june, all i can say bout it is that its the best hotel i've ever stayed in. Lots of reasons for this but in a nutshell staff absolutely fantastic from the cleaners to the entertainment staff. Also, just the general atmosphere of the place, everyone was having a great time.
Went to the Riu Cancun once, from what we seen of it, it was basically the same as the Caribe although it had more of a grand look about the place as is visible from the outside, but we got the impression we were staying at the better hotel.
One small downside is that you need to take the bus or a taxi to the clubs unless you like long walks.
Hope this helps.