Travel from Ninh Binh to Hue

Hello everyone !

My husband and I are going to Vietnam in the next few weeks and we're wondering how to travel from Ninh Binh to Hue. Is it better by train or plane?

Maybe some important points:

- We have about four weeks in Vietnam (return ticket not booked yet) so we're not afraid of 'losing a day'. We are however concerned that the 11 (maybe more?) hours of train are gonna be too much?

- although we're watching our budget, we can afford the plane tickets.

- since we're mostly considering the train because of the scenery (and I'm a difficult sleeper), we would be travelling during the day

The other advantage of the train is that we could stop somewhere along the way for a night or two. If anyone has any suggestion in that regard it is more than welcome.

Thank you!