i've applied with a 160/3.7, and i think my soft factors may have contributed to my being waitlisted. as far as evaluating individual chances, unless you're an admissions counselor at vandy, i'm not too interested in reading speculation, but instead i am more interested in hearing from someone who has gone through or knows about the waitlist at vanderbilt, for example- how many candidates are on the list, how many do they typically take off, since they do not rank candidates, what factors help them decide? things like that...
The number of people on WL depend on the school, not sure with Vandy.
The greatest thing you can do to help your chance now is by writing them a letter explaining why you are still interested in Vandy and explain any progress you have made since you submitted the application (any new honors, awards, etc...) If Vandy is your #1 choice, be sure to make this impression in your letter as well.