Is it part of your vacation or just a place to sleep?
We live in South Florida and have stayed at the Marriott Harbor Beach for mini romantic get aways and also as a mini family vacation. We live about 8 miles from the resort - so obviously it is very nice.
If you are wanting for this stay to be part of your vacation - then it is worth the extra money. The hotel is beautiful, the restaurants are outstanding, the staff excellent and the beach is wonderful. If you can get your flight to come in early, you could check in and have a wonderful start to your vacation.
But, if you have a late flight and are not going to have time to enjoy the property - then perhaps the Marriott Courtyard will work fine. I say it is a vacation and try to book the extra time to enjoy Fort Lauderdale if possible.