Actually I think that Hyatt is probably the easiet place to catch a cab in the entire city. They usually just line up on state street right around the corner. If you talk to the doorman at the hotel, he can usually get you one in less than 2 minutes (I actually used to valet park at that hotel, back in the day).
I would have to disagree about the ease of catching a cab in columbus though. I have been out late (after midnight), in the short north/arena district and had to call cabs and wait for over 20 minutes for a cab to show up. I haven't spent much time in other Ohio cities, but the little time I have spent, I don't remember it being easy to get a cab. I am comparing to some where like Chicago, where 99% of the time you can wait by the side of the street and hail a cab in under a minute. That's what I would say is good cab service.