I am looking for a comfortable operating height for a yard and industrial area on a two level N scale RR. I am 6'2" and have had layouts with yards and industrial areas at 53" or more and was very happy with that. That said it still was not ideal eye level for me. I was thinking 60" for the yard plus industrial area and the rest of the layout would be lower. Scene depth would depend on scenic needs and switching areas would be staggered for that reason.