I have only been on 5 cruises and only once did I feel the need to wait in line for guest service and it was premature on my part.  I checked the kiosk when I boarded to see if my $4oo was applied to my account.  The Kiosk did not reflect it so I finally was able to speak to the rep and she showed me that is was and so did the TV channel in my cabin.  Other that I never once felt the need to see them.  Why are the lines gigantic at the service desk?  What possibly could these 100's of people a day possibly need?  How can so many people have so many issues?  Boggles my mind.