I am going next year in Fecruar/ March yes to Anguilla and St. Martin. On the way there I have 4 nights stay in Miami, on the way back 3. I am thinking about where to stay best. Basically, I am particularly interested in sightseeing, beach does not play the biggest role for me. Partly I will also be on the road almost the whole day.
For the first 4 nights I tend to a hotel in downtown, even if I could of course just as well live in Miami Beach. But I don't really see the point of paying a huge surcharge for a beach that is not the mega hit at that time anyway.
In Downtown, I fluctuate between Mandarin Oriental and Four Seasons. Both I do not particularly like, but is much cheaper (still overpriced by the way) than in beach. Other ideas and comments.
The last 3 nights I would rather go to beach. Surf Club is my favorite, but also expensive as hell. Acqualina is more expensive than Surf Club for the 3 nights, as is Faena. St. Regis in a double room would still go, suite is on Surf Club double room level.