When it comes to races on the track my favorite by far is the 10,000. 25 laps around a 400 meter track. It is so perfect. Just look at it. There are four zeros! It is also an incredibly telling race. As a rough indicator of running ability competitive runners are either 20 something or 30 something runners. I can think of no more fitting barrier between good runners and really good runners. Sure the sub four minute mile is one of those barriers, but I believe that as the running event gets longer there is more training that you can do to excel. That is to say genetics are more important in the 100 meter dash than the marathon.
At WPI on the track team I have become known for endlessly recruiting young runners for the 10,000. I like to imagine it has paid off. When I first ran it my sophomore year I was the best 10,000 runner on the team at just under 35 minutes. Last year we had three runners qualify for D3 New Englands with sub 34s. WPI has specialized 10,000 training and it is now one of our strongest events for distance runners. If my protoges carry on the tradition I am sure WPI will send someone to nationals in the near future.
If you still don't understand the beauty I'll try to explain. It's hard to fake a good race. You can run a decent race on minimal training but not a good race. If you want to be good at it you have to train for it. The 10,000 is a long event. You can only run a few in a season before you are flat and burnt out. When you stand on the starting line you know than it is going to hurt in half an hour. There is a certain confidence and fearlessness about running a 10,000 that the 5,000 or the mile just do not have. You will not feel good the next day.
One final benefit of the 10k is that it translates to other sports. There is a 10k open water swim, 10k long track speed skating, and 10k cross country skiing in the olympics. There are 10k bicycles time trials. It is a very round distance and popular in many sports. It is short enough and long enough to be a strong test of speed and endurance. Go out and do a 10k!