We were there with kids this past Spring Break and visit family there frequently.
Typically we're disappointed with the Cuban...but like The Latin Cafe which is around 26th street. Good, not great. We've been generally disappointed with everything in little Havana except the cigars
There is a very nice French bakery to get breakfast on Biscayne...Provence.
This last trip we were extremely pleased with the Chilean restaurants. Ate at two or three just north of downtown. Great seafood.
The design district restaurants really weren't great for kids. A little too formal and our kids would have been more pleased with $12 hamburger than a $35 piece of meat.
The kids did enjoy the beach. My 11 year old asked why people weren't wearing bathing suits. We explained that they are European and Europeans don't wear suits to the beach.