wow i really disagree with the previous poster. yes the beaches are not what they used to be, but they are still nice. and i swim every time we go and only in the ocean.
that being said, you do need to book room on the top of the seven if you go there to swim during the winter months. we stay at the riu.it is not the ritz, but it is nice for what we go for. it is gorgeous inside and out. the only thing that is modest are the rooms. and they are very clean and have a great balcony with stunning ocean views.
based on what i think your needs are as far as swimming i would change and go to the riu palace or riu cancun.
there might be some on here who can testify as to how the beach is at another hotel, the excellence playa mujeres. same water as the other 2, but way more luxurious. read those reviews also.
p.s. thank you for the sacrifices your hubby and you and your family make for our country!