Khayden,
Being pretty much old school I still use the old grass type inside/outside carpet with some old block style acoustical tile under it to deaden the sound on my 1st level, works real well in our formal living room at Christmas time. However the larger game room/office layout had no carpet or tile and I actually liked it better, simply stained green and painted in different areas for roads and snow, it was super easy to work on. I actually liked hearing my trains run on all the different levels. It all depends on what you want to accomplish with your layout, don't let some else decide for you what you want, advise is always nice but it's your layout build in the manner you most like.
PCRR/Dave