My layout, when it's completed, will vary from 36" to 59". The lower height is less than I would have liked, but was necessary to accomodate the part which is 59", which will form a wide shelf over top of the lower section. As it is now, I use office chairs on casters to follow the trains around the room, although the layout is still well below eyelevel. The upper level, when built, will still be below my standing eyelevel, but will at least allow manual uncoupling of trains, as per my operating practice. The layout, an around-the-room design, is generally in the form of a very convoluted "Y", with the stem of the "Y" at about 44" height, with fairly long grades up or down to the other levels. There are stacked staging yards at 36", 44", and 59", with operations from any point of the "Y" to any other point. There is also a very steep run-through between the 36" and 44" levels, useful for locomotive break-in running, or when somebody just wants to see trains running. My Grandson, who is four, has been viewing the trains (and running them) since he was about 2 1/2, using a small step-stool. By the time the upper level is built, he should be tall enough to view it without assistance.
Wayne