Lou,
I have been toying with going the opposite direction. Instead of going up to a second level I am developing a plan for a "wedding cake" layered type layout. The top level would be narrow, say maybe 8 to 10 inches and somewhere along the line the track is going to disappear and go down to the next level that will only be about 3 inches lower but will extend out from the bottom edge of the facia board of the upper level about another foot or so and maybe even drop down to a third little narrow shelf for a long branch type line that would be built extending out from the bottom edge of the middle tier's facia board. This would allow for long run times, keep the grades really within reason, maybe 1% or less and still keep the layout fairly narrow except in the corners and the ends.
prof