I've been to both. I liked Paradise better. Both are nice.
Paradise is free and has nice chairs and the restaurant/bar is good.
Playa Mia has different charges, one is all food buffett and drinks for one price. But there were rocks on beach and the chairs suck. I can't remember the website prices, Hopefully they will have it fixed soon.
Paradise is a little closer to ship, they are on the same road not far from each other. Just take a cab and they will know where it is.
Both have clean restrooms/ changing areas.
You'll enjoy either one of them.
There are cabs that wait there when your ready to go back to ship.