We are looking to travel somewhere warm in December of this year, for approximately 3-4 weeks. We are originating from Canada – Alberta, to be exact, and have done a fair bit of travelling throughout our lives, however, we are now bringing along our 4 year old son. With that in mind, I suppose our biggest concerns are now flight durations and safety (in our younger years and without children, these weren’t so much a factor, but definitely are considerations now).
Aside from Indonesia you might also consider Thailand, which has great infrastructure so it’s much easier to travel with young children. Phuket has by far the most options, and its rainy season usually ends in early November. For families I recommend Kata Beach and Karon Beach, which are both just south of the main shopping and nightlife town of Patong Beach.
Southeast Asia is easier to deal with, and there are cheap flights connecting in the Middle East and landing in Bangkok, Kuala Lumpur, and Singapore. Each of those is a very interesting city, and there are many smaller places to go in the same region. In Malaysia there is Penang and Melaka. In Thailand there is Chiang Mai and quite a few others in that area. In Laos you can visit Luang Prabang, which sounds like it could be a winner for you. And there is also Siem Reap, which is home to the amazing Angkor Wat temple complex.