Polar Express - Baby Madison -vs- Heavyweight

The heavyweights will not look right with the Berk from the ready to run set. Stick with the baby Madison's unless you plan on getting the scale Berk. 

The two sets are in two entirely different worlds and are not interchangeable. The original set introduced in 2004 is an 0-27 set, while the scale set requires a minimum of 0-54. There is a sizable difference in cost. Yes the scale PE coaches have more detail and have interiors verses silhouette  window treatments.

Depends just how deep your interest in the Polar Express story and how much you want to invest to recreate the train part of it. Lionel in it's 10th Anniversary offerings has re-introduced the scale 1225 Berkshire and some of the scale passenger cars. Check their Christmas catalog, but don't expect the 0-27 pricing or you will have some serious sticker shock.

Below is a photo of the scale 1225 Berkshire and one of the scale PE passenger cars. Please click on photo to get a larger view.