We're most likely doing Ocean Key Resort, seems like a really great deal. It all depends on if you want a ceremony on the beach, since they only have the pier. The view looks amazing though. We're doing a cruise to Key West and Cozumel, so this is right next to the port, which saves on transportation costs. Comparing Ocean Key Resort with the Hyatt, Ocean Key doesn't have as much of a wedding coordinator, so you may to hire more outside vendors (wedding planner, tent, linens), but I'm not sure what the Hyatt includes.
Also, we found this Key West Webcam, which was really helpful in deciding our location:
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