Hi I'd like to travel to Hanoi with my friend and her wheelchair bound daughter. I have been there twice and think if we stick to the old quarter we should be OK. But would love to hear what others think as I wasn't really thinking about wheelchairs when I was there and I might be wrong
On one hand, I'd like to say why not? A wheelchair shouldn't stop her from travelling and as long as you are prepared for the challenges, go for it. On the other hand, I'd say you're going to have one hell of a challenge! First thing is when you book your accommodation, ensure that there is an elevator or that you have a room on the ground floor (noisier). A majority of the hotels have rooms 2-4 floors up - with no elevator.
Getting around the streets will be difficult - narrow sidewalks with many obstructions in the way (tables and chairs, parked motorbikes, signs, people, etc, etc). It's not impossible but it will be challenging. And of course, crossing the streets there is a frightening exercise for anyone at the best of times. If the daughter has a nervous disposition, it might be quite stressful for her.
I always remember seeing a man who was without legs, crossing the streets in Hanoi on what was basically an oversized skateboard, essentially sitting on his torso and using his arms to propel himself along the street. It looked as scary as hell but I was amazed with his tenacity to get around.
While Hanoi is my favorite destination in Vietnam, I think it must be the worst place for handicapped access. Even where elevators exist, there's often a step or two before the elevator or escalator. I would think that Hoi An would be a much better destination for your handicapped friend.
As Buzzylizzy mentions, it will be essential that she has the right attitude going in - that she isn't stressed in traffic and will try and take all the frustrations and difficulties as something to laugh about, and you'll probably need to have backup plans /contingencies for everything, because I'm sure miscellaneous steps will pop up a lot (as Daawgon mentions).
Remember: in much of Asia, sidewalks aren't for walking on, they're for parking your motorbike or setting up your shop/restaurant.... She will be essentially riding in traffic, weaving around parked vehicles and obstructions at the edge of the road, rather than on the sidewalk. I'd ensure her chair has something to make her more visible, to avoid any mad motorbikes in a hurry darting around parked cars and right into her because they didn't notice her in time.