We stayed at the Loews Miami Beach for a long weekend in April 2009. The Loews is a beautiful hotel in the heart of South Beach, within easy walking distance of many restauarants and the Lincoln Road Mall which is a large open-air pedestrianized area of several blocks. The pool is large and very pleasant (maximum depth is 6 feet, so need to watch your little ones). There is no water-slide, however. The hotel is also right on the (very nice) beach, where umbrellas and lounge chairs are available for rent.
The rooms were clean and spacious (we had 2 connecting rooms, one with a balcony). Each room has its own thermostat. My only complaints about the rooms are that the safe was not large enough for a notebook computer, and there was only one sink in the bathroom (I know, I am spoiled).
My main complaint about the hotel as a whole is the large number of smokers. Of course smoking is no allowed inside the hotel, but on the way to the pool you will encounter many people smoking. Several people also tend to sit right on the edge of the pool and smoke, not just cigarettes but also cigars. Several times there seemed to be a cloud of smoke floating above the pool, which (being a non-smoker) I found quite unpleasant.
Also, one day we rented a pool cabana for the princely sum of $450. Comfort, privacy and food and drink service! Yes, and also someone smoking a cigar not far from the entrance to our cabana, so that we were continually bothered by the smell of cigar smoke blowing into our little paradise. Obviously this hotel wants to attract a younger crowd and has a liberal (outdoor) smoking policy, but do beware if you have young children or are bothered by cigarette or cigar smoke.