Any opinions on airport shuttle services in different cities? I have conferences in New Orleans, LA; Denver, CO; Pasadena, CA; Boston, MA this year, and don't plan on driving around to make a rental car worth it.

I was looking at some airport shuttle services online but the websites are much more, uh, skeezy, and not user-friendly, not to mention some companies requiring you to call on the phone for any changes to the reservation.

The last time I used a shuttle service was when I was in college. Would like any opinions on services, etc. If there is a forum thread about this, I didn't find it, and would appreciate a rethreading if that's appropriate.

-T