We loved travelling around in Vietnam, then again we didn’t travel by road for most of our journey, although we did do several day trips.
1) If you are taking a bus anywhere, get a seat on the right hand side (opposite the driver) as you will be shielded from all the honking on the drivers side. Cars passing the bus in either direction will often honk vigorously as they pass, which can disturb your sleep. Don’t expect too much sleep while riding in a vehicle as the roads are bumpy, and your head will bounce around alot.