If you're looking for an amazing beach vacay with sugary sand beaches, a Florida Keys roadtrip may not be quite what you're looking for.  While Florida is known for its beautiful white sand beaches (on the Gulf side), you'll quickly notice that beaches in the Keys don't live up to that.
The Keys were formed atop coral reefs and are protected by those reefs, meaning the islands don't have sandy beaches.  They're usually rough and covered with pulverized coral.