It depends on what you are looking for. In general I would say the Gulf side is a little more sedate than the ocean side. I have been to Marco Island but not the Marriott timeshare. The beach there is great and there are good restaurants on the island. Good for a younger family. I own at Marriott BeachPlace in Fort Lauderdale. Beach is also great, usually waves are bigger and rougher. Condo is a former 17 story hotel and is across AIA from the beach. It is in the middle of the beach action, retail/restaurant/bars area, so restaurants are walkable. I think there is a lot more people action there especially during spring break times. Better for high school and college. My opinion is that golf is better in Fort Lauderdale than Marco with more courses to choose from and they tend to be a little cheaper. I am not that familiar with other Marriott ocean resorts.