I started to take longer night flights when I was working on getting my UA MM status. Also, I would search for upgrades and many times flew ord-iah-cdg....or wherever I could be confirmed. Wonder why I didn't do it before I actually needed the miles, I continue to do it.
My adult children take my grandchilden to Europe twice a year, always the late night flights and try for longest flts. The kids sleep and adjust quickly to the time change.