We are just returned from 4 nights/5 days at the Loews Miami Beach with our two kids (ages 3 and 6). This is a great hotel to stay in if you are seeking quiet sleeps in a booming location. Loews is right between Ocean Drive and Lincoln Road so, yes, the nights are wild and raucous on South Beach however the rooms are clean, cool, quiet and comfortable. We really like this location and stayed here again this year - same way as last year.
Pros of the Loews Hotel: Location, location, location. Good pool, nice rooms, good beach. Staff are kind, professional and work hard to make people comfortable.
Cons of the Loews Hotel: Rooms are smallish, can be pricey, some rooms don't have balconies which would be a deal-breaker for us
Overall, if you are familiar with South Beach you know there are very few nice hotels that are also quiet and clean. You also know that location trumps most everything else so you can walk everywhere and enjoy the atmosphere. We would absolutely return.