Hello Suzi - I just posted a separate thread about this very concept! I had a decent layout (24' x 16') some years ago using ScaleTrax and really liked it. After awhile however, the odd tie spacing got to me and a move necessitated dismantling it. Since then I have been (reluctantly) acquiring a good supply of Atlas in the event I am able to build another large layout. :-)
Check my thread on the Atlas forum "Hey Atlas... "