Vietnam
Vietnam is long, and most itineraries run north to south: Hanoi and Halong Bay, then Hoi An and Hue in the centre, then Ho Chi Minh City and the Mekong Delta. Internal flights make the distances workable.
Bali
Bali works as three different holidays depending on where you base yourself: Ubud for rice terraces and temples, Seminyak and Canggu for beach clubs and surf, and the Bukit peninsula for cliffs and quiet. Most itineraries split across two of the three.