take 4:15. that's what we did. the train will be less crowded, and if you are sitting on the left (which is the best side), then when they make you switch sides at the top (I assume by your description you are going up and back) then you may not have to switch sides, which is what happened with us.
I cannot tell you how breathtaking that trip was. absolutely stunning. one of the most spectacular things we have ever seen