Is this Vietnam + Cambodia itinerary good?

Hi everyone! Planning a Vietnam + Cambodia trip for December 13–27 and wanted opinions on the distribution of nights and whether you’d change anything.

Current itinerary:

Ho Chi Minh City – 3 nights
Siem Reap – 4 nights
Hoi An – 3 nights
Hanoi – 4 nights

Planned activities:

Explore Ho Chi Minh City + Mekong Delta day trip
Explore Siem Reap + Angkor Wat sunrise + temple day + Kulen Mountains day trip + Floating village day trip
Explore Hoi An + Da
Nang (possibly Ba Na Hills)
Hanoi sightseeing + Ha Long Bay day trip

Does this distribution sound balanced to people who’ve done similar routes? Would you change the number of nights anywhere?