Areas at Vail with more difficult terrain:
1. Northwoods area. There are a few hucks if you want them, and some short steep sections. It is gladed.
2. Steep and Deep and the line right next to it between S&D and Iron Cross. Pretty steep (short), with some tree alleys to keep your attention. The way out is a bit flat and disappointing, but ..
3. The area all the way skier's right in Sundown Bowl. A steeper line.
4. Genghis Khan. One of the steeper lines in china Bowl.
There's some mixed tree skiing on the frontside, but I don't remember the names of the runs.