The Indigo Pearl on Nai Yang Beach is a great property...The Movenpick Karon is also good but popular with families. I've heard lovely things about the Katathani Beach Resort as well as the Avista Hideaway Resort.
I tried booking through an agent and I highly recommend Gail. She will help suggest and book the best resort for you according to your budget and requirements..055 9569502.
Maldives is great to relax..try the Kurumba resort which is only a short speedboat transfer, has a great kids club and won't break the bank! I had a friend in the travel business sort me out for a wonderful stay there recently :) In fact I totally recommend Gail...
Mauritius is wonderful for families too! The west coast probably has more resorts than the east coast.
Flying time around 6 hours approx. for Maldives and Mauritius. Bali is much further away and not directly connected...so probably wouldn't recommend it for families with smaller children!