I've only been there there on a business trip i.e. Suva so I'm sad to say my experience of Fiji reflects that of Dan.
As for the family holiday thing, on our recent holiday I found that I could get up early before everyone else, head down to the beach for a quick sunrise timelapse and be back at the room before everyone else had woken up. So my tip is to look for a hotel on the beach facing east :-)
example
Sunsets are a no go with dinner plans etc.
The kids are going to love it.
James