Thanks lally. Apartment option is always a favourite with us so will look into that. Anyone been at Christmas to any beach resorts too? Would try and do city and coast.
We've just returned from Ho Chi Minh City with 2 children (although slightly older than yours) and wanted more room than 2 hotel rooms would give us and so stayed at the Saigon Domaine Residences. They are serviced appartments but also have a decent sized pool. We booked a 2 bed but were upgraded to a 3 bed and had loads of room. They are about 20 minutes drive outside the main area of HCMC (and 45 mins from airport) but they have regular, free, minibus or speedboat shuttles or a taxi is only about $6.
Unfortunately their website isn't brilliant but TripAdvisor has more information. HTH