I am going to UCSF this Fall, and I definitely think my post-college experiences helped me in the process at UCSF. From what my tour guide said, at least 50% of each entering class is non-traditional and that in many years it is closer to 2/3's. However, this is anecdotal, so take it as such. I think at most schools, being non-traditional is an asset, provided that you have numbers to back it up.
As to schools that are not as non-trad friendly, UCLA tops my list. They used to state that those over 27 had little to no chance of acceptance; however, in today's litigious atmosphere and sensitivity to "age discrimination" at any level, UCLA has changed its marketing. The policy, though, is probably still in effect. Who knows for sure -- I bet there are some people older that this who have gained acceptance.
If you have attended professional school after college and did not finish your degree, I would steer you away from Georgetown. They frown upon this "behavior" and believe it is an indication of an applicant's inability to finish medical school. (I got peppered with "how do I know you'll stay in school if I let you in?"-type questions. It was a fun interview.
Other than that, I'd say it is always good to look at the "average age" of entering students. Keep in mind that most graduating "traditional" students would be 22, so anything at or above 24 would be an indication (to me) that the school accepts a good number of non-traditional students.
I hope this is helpful. But, keep in mind this is based only on my experiences; for each positive or negative I had, someone else probably had the opposite. Good luck!
