This information is posted for those like me who obsess about the unknown. If you are not a novice skier going to Vail for the first time this will not interest you. I had only skied two days on Midwestern ski hills before going to Vail Mt. The thought of skiing the West was quite intimidating. Here is my opinion on what trails to tackle first and the relative difficulty of each.
Ride up the Lions Head Gondola and take the Game Creek Trail (catwalk) into the Game Creek Bowl. Ride the lift out and take Eagles Ridge back down to the gondola. This is the easiest trail (excluding catwalks) on the mountain.
When that loop is easy try the Lost Boy (relatively easy except for a steep section at the beginning and at the end) or take the Overeasy down to Mid Vail. You could take the Meadows down but it is a little steeper. (as a note you will need to keep your speed up on the Meadows because there is a long flat area before the final decent to Mid Vail)
At the top of the Mountain Top Express Lift you have three choices. 2 green runs and a catwalk to the sourdough area. Between Ramshorn and Swingsville I think Ramshorn is easier. The Timberline Catwalk is quite steep (blue) for the first 50 yards and then it is very gentle all the way to the Sourdough Lift. (It is worth it to brave the steep section in order to get to the Sourdough area. It is the best area for a beginner) Every green from this lift is nice for a beginner. They all have a common short steeper section where they come together at the bottom of the Sourdough Lift. (The easiest is Flap Jack and progress in pitch as you move toward Whiskey Jack)
Now after skiing a few days are you ready for some blue? Whiskey Jack off of the Sourdough lift is a great place to start. (In my opinion it is no harder than the greens serviced by that lift) From there I would progress to Christmas and then Cappuccino (if it is groomed). By this time you should be able to handle almost any other groomed blue on the mountain. Columbine and Lodgepole are always nice runs. On the lower mountain Born Free and Simba are nice long gentle blues. Dealers Choice in the Game Creek Bowl is still tough for me. I think it is a mental thing because I had a hard fall near the bottom of that run. I don’t attack that slope like I do the others.
Just a few other notes, if you are ready to go down the back bowls try any groomed blue in the China Bowl if it is a clear day. Since there are no trees there, it is almost impossible to see where you are going in a fog or snow storm. If visibility is poor, I would take Sleepy Time Catwalk over to blue sky basin. I skied all of the blue runs in blue sky basin and found them about the same. (Beautiful runs cut through forests with a tree or two hear and there in the trail. Similar to Cappuccino) Be careful of the fist corner of the Cloud 9 Catwalk. There are a lot of accidents here due to high traffic, narrow lane, and bumpy snow.
If you are ready for more, break in a black on Avanti when it is groomed. It is just one short steep section and then it is back to gentle blue. I hope this has been helpful to someone. I would have loved this information before I went to Vail for the first time. Next year I will go back and have to gather my own information of the relative difficulty of black diamond runs at Vail, unless someone more experienced publishes a guide to them.