My wife and I spent 4 days on South Beach, and had a great time at Essex House!
Its two blocks from the beach, and right on Collins and 10th; so its right in the middle of the action!
You can walk to either side of south beach within 20 minutes. We were able to walk to all bars, clubs and restaurants with ease.
With the stay at Essex House, you will also get free access to the Clevelander at night.
The staff is very helpful, and will give great restaurant and bar suggestions