i usually drop off at a ups store and i've never had any problems doing it that way. once i took a package to the sorting facility (where they also have a fully staffed shipping center) and the package got missorted and didn't make it to its destination until the second day when it was supposed to be next day air. go figure--i went the extra distance to take it straight to the facility and it got messed up.

anyhow--my vote is for a ups store. an authorized location is usually just a business that takes packages and then ups comes and picks them up each day but the business itself isn't actually affiliated with ups.