Christmas between brisbane and England!

[3boysNeedABiggerKitchen]

We are hoping to get together as a family for Christmas 2019. Some of us live in the UK, some in Brisbane. Ages from 3-75, about 15 of us.

I am looking for any advice on good places to go. We are realistic that flights at that time of year are expensive so we need to book early and hopefully find a location that is not too expensive for daily living.
Happy to organise the trip without an agent.

We are reasonably adventurous, but have a wide age range to cater for!

We love sports and activities, especially water based.

Does anyone have any experience or recommendations that they could share?

Vietnam is good value. With my family I've been trekking in spa, Vespa tours in Ho Chi Minh, visited great museums and temples and eaten fabulous food.
South is much warmer in December, but not sure about water sports. Perhaps phu quoc Island or check weather in nha trang in December.
Cambodia is also excellent value, but not sure about water based activities as sihanoukville does not have the best reputation. Not sure what Kep is like.

Thanks, i will take a look at those options. I also want to look at Sri Lanka but need to check the current FCO advice