There is not a lot of information about chill requirements for flowering cherry trees. However, a rule of thumb is that "the chilling requirement is the total number of hours required during the winter for a particular cultivar to induce the tree to break dormancy and produce flowers." (http://www.chestnuthilltreefarm.com/Chilling-Hours.html) Remember no flowers, no fruit.
Look for flowering cherry trees with low chill requirements, the further south your garden is located. These will be prominently featured in any description. There is an interesting discussion of flowering (and fruiting) in FL cherry trees (both ornamental and fruting) here: (http://www.mombu.com/gardening/gardening/t-cherry-trees-in-florida-cherry-have-moss-2739622.html) Trees with high chill requirements are more suited for northern gardens. Because so many flowering ornamental fruit trees are grown in the north, there is usually no feature of chill hours.
Examples:
1) Taiwan flowering cherry, Prunus campanulata (family: Rosaceae), is a deciduous tree growing 20 to 25 feet tall. It has good heat tolerance and low chill requirements for flowering, making it about the only dependable flowering cherry tree for Florida.
2) Prunus serrulata “Kwanzan" (family: Rosaceae), blooms in April, its large, double, deep rosy pink flowers hang in clusters just as the reddish young foliage begins to appear. Like most flowering cherries, the “Kwanzan” provides the most brilliant display of flowers in a climate with a winter chill. Prune in winter to shape. (http://realestate.msn.com/slideshow.aspx?cp-documentid=23948393#5)