I am one of the fortunate ones who lives in LA, so I have 6 boutiques nearby (anywhere from 15 minutes to an hour drive). I usually tend to look online first and then go in store to look. I have one go-to rep at Rodeo Drive who I send most of my questions (since they can get almost anything), and sometimes I will check in with a few other SA's that I've collected at the other locations.
I personally couldn't order online without seeing in person because, as someone else pointed out, bags can look different in person and also on your person.