If you're looking for a hotel in South Beach during Memorial Weekend, serious ballers need only apply. I just did a hotel search for availabitly in South Beach from May 27 - May 29, and the rates have gone through the roof. 2-star hotels are charging over over $300 a night.
Here's a tip: You can save hundreds of dollars that weekend if you stay in Downtown Miami. The chain hotels are nice, and they're just 5 miles from South Beach. Here is a list of hotels in Downtown:
• Clarion Hotel & Suites
• Conrad Miami Hotel
• Miami Marriott Biscayne Bay
• Riande Continental Bayside
• Radisson Miami Downtown
Links: Hotel Search, Miami Downtown Hotels