It's not the Orient Express, but Vietnam's Reunification Express is a great, fun way to travel. We travel 'Soft Sleeper' on all rail journeys. This is the most comfortable standard available though it cannot be compared with European standards.
Victoria Express train is the best train in terms of comfort and services from Hanoi to Laocai, Victoria "Orient Express" stylish train offers one restaurant and two luxury sleeping carriages, all with air-conditioning.
Tulico train offer comfortable, air-conditioned soft sleepers. While this is not a luxurious train, it offers good alternative transportation to Sa Pa from Ha Noi.