I've hunted the beaches of Florida both east and west coast for the last 15 years for three months every year. Here is what I have found.
All the major beaches are hunted hard daily and for the last few years, the sanding of the beaches has made hunting hard. But there are some areas that do get washed away and so you need to hit those areas. I also find that the less used beaches don't attract the hunters which means that there are places that have very few people hunting them. You need to find those areas as the stuff dropped there will still be there even if there is less dropped.
The most popular beach in Florida is South Beach in Miami. There are tons of folks detecting the water and beach there every day. When I was there for two weeks, every day the beach I had at least 6 hunters in sight. I've hunted the Treasure Coast and found that for the last few years, the beaches there are so sanded in that nothing has been found. Often times while I was there, there was no one on the beaches....not even a swimmer. I stop in to the McClartey Treasure Museum to check to see if anyone has reported finding anything. This last year almost nothing.
The East Coast beaches like Daytona and Fort Lauderdale may have some good hunting depending on the time of the year. Spring break brings lots of college kids with rings and blings that often get lost. Lately, due to the cost of gasoline and the economy in general, those beaches are not as busy as they were prior to Bush/Obama.
The west coast of Florida has some places you may like. I love the beaches of Sarasota as the money is there. But Siesta beach is hunted so hard that you need to hunt low tide usually at night as most won't hunt late. The early bird gets the worm.
I've hunted Sanibel and found very little there. But I have heard that there have been some great finds. It's all about timing I guess.
Make sure you lock your car and don't leave anything of value in your car. I've heard that cars have been broken into at many of the beaches. The economy seems to be a double edged sword. The price of gold is way up but the gold being lost is way down due to people selling their gold or not going to Florida due to the high price of gasoline.