Hi there are a number of good places to stay in Fiji for the travelling family. If you are wanting to go to the outer islands something that everybody should do then I would suggest Plantation Island Resort. This is a family friendly resort with kids club and lots of activities for the kids. The resort has various types of accommodation and also has meal plans.
On the Coral Coast which is on the main island of Viti Levu there are a number of resorts for families. However, The Naviti is a good choice as they have an all inclusive plan (accommodation, all meals each day and local beer, wine, spirits and soft drinks) Kids Club, beautiful swimming pool, good restaurants, and golf course.
Nadi try the Sonaisali Resort about 20 minutes out of nadi, has kids club, good choice of accommodation, swimming pool with swim up bar, good dining and activities.
All of these resorts can be booked on the internet but check with travel agent they may have package deals available.
Hope this has been of help and hope you have a great holiday.