I need to be in Miami towards the end of April and I have two Marriott free night certificates (the one's that cover up to 35k points) that will be expiring right after that, so I figure I may as well use them for this stay. The (eligible) choices are pretty underwhelming, so I wanted to see if anyone has recommendations.

The event I'm going down there for is short, so I'd like to be on the beach (not across the street) and ideally in South Beach as that will be the most convenient.