The Glenwood Dunes trail is near the eastern end of the park. I find it to be the most the most “woods” like of the Indiana Dunes trails. While the trail is in fact sandy it is pretty well packed and contains a fair fraction of soil. There are really only a couple stretches where the sandy dune nature of the land is readily apparent. 
It is the longest of the trails in the Indiana Dunes National Park. It breaks down nicely into two 3ish mile hikes that I unofficially refer to as the east (in green) and south (in blue) legs. The east trail begins at the USGS Lake Michigan Ecological Research Station just off of US12 and runs the length of a dune ridge. The south trail head is located off of US20 and passes through more lower lying wetlands with a couple of short stretches of board walk.