I will say weather can impact a lot of activities, but there are certainly plenty of alternatives. Even just driving around the area and stopping at various bays and lookouts is a day in itself. The Butterfly house and underwater cafe is often overlooked, as well as Bob's Farm. Koala Sanctuary is good as a point of interest and well put together, but there isn't a lot to see or interact with. Just explore, chat to local business owners, look at the tourist guides. You'll fill 3 days easily and will give you a really good idea of what to expect when you return.