Hey Jay: Last year I went through exactly what you are going through now trying to understand how "trail" effects handling. One problem, as you can see from reading this thread, is that people have a tendency to get things backwards and say the opposite of what they mean when discussing trail.

To put it as simply as possible, trail is the distance between the bottom point of your tire (where it sits on the ground) and the point where the steering axis meets the ground (an imaginary line down through the center of your head tube to the ground). It is called trail because (on almost any bike) the contact point of the tire trails the steering axis by a small distance.

The more trail there is (i.e. the closer the wheel is tucked up under the frame) the quicker it will tend to steer and the less stable it will tend to be. The less trail there is (i.e. the further out in front of the bike the wheel is placed) the more stable it will tend to be). People constantly get this backwards, though. Probably because it is counter-intuitive to think that the further a bike sits behind its front wheel the LESS trail it has.

As others have pointed out, though, trail is only one factor in how a bike handles and feels. If you are used to riding modern road bikes you will probably prefer the greater trail of the CoMos or Burley Race Package. If a more solid feel and less wobbling when the stoker shifts weight is more important, you'll probably prefer the shorter trail of the regular Burley's Treks, Santanas, etc. There is obviously no substitute for a test ride --- but finding the bike you want to test can sometimes be a challenge.