We have reserved our seats in the upper cabin for both legs of our journey but I have read a few times the arm rests don't go all the way up in the economy section. My plan is for my son to lay across us to sleep so I'm now wondering how far the arm rests go up. It's not so much of a problem going out its mostly coming back. Has anyone travelled in both the upper and lower decks with little children? Is one more comfortable than the other?