You want to be in South Beach....any hotel on Collins, Ocean or Washington....anywhere between 1st and 17th or 18th street.
I wouldn't book so soon as the dates do change every year. The past few years DT had been playing Space the Monday before the Conference, we booked in advance expecting that, and he ended up playing the Wed. before, so I would wait until they announce some dates first.
Some good hotels are the National and the Delano....but honestly you are better off saving your money for going out and booking in a cheaper hotel (who the hell spends that much time in their room anyway) I have gone to the WMC the past two years....and it is the closest thing to Ibiza...I only like Ibiza more because it is a far trip for me (Miami is a 2 hour flight)....but the WMC is great!!!!! (Like I said wait until they announce some stuff...there were even rumors of the WMC being moved to Vegas last year....big mistake in my opinion)