Heading to Vietnam in Dec/Jan for about 3 - 4 weeks. Planning on Doing the North the Flying into Da Nang. We have 3 teenagers 17,15,13 and want to have a few days relaxing on the beach before heading off to HCMC and the Mekong Delta. Wondering if Mui Ne or Nha Trang would be better suited for the family. Or should we skip these places and head to Phu Quoc Island.