It's a lot cheaper to fly into Fort Lauderdale and there is a great Hotel on the beach, called the Grand Pelican. Fort Lauderdale on the beach is a lot like Key West, they even have a sloppy joe's and a pretty good strip of bars as well as a shopping district with a ton of shops catering to Brides (Las Olas). Its a much more casual place than South Beach. But I think in either option you should still pick the place that is going to work the best for you.