We also shoot for arriving when it opens at 10:30.....if you arrive before that it is a waste as they will not even let you in the parking lot...at least this was our experience.
They usually start boarding about 12:15 or so. If you don't want to wait in any line arrive at about 12:30 or 12:45 and you will pretty much be able to walk right on the ship as the majority of people will have already boarded!!!
We like standing in line and people watching...plus the characters come out, there is a coffee shop and TV's playing Disney cartoons for the kids. Not everyone in your party has to wait in the line. We usually have 1 or 2 waiting in line and the rest of us walk around the terminal and then switch, so not everyone is stuck in one place the whole time.
We have never had a problem getting back into the line...people know who is in front of and behind them and they realize people need to get off the line and come back....everyone is very nice!!! We ususally tell people around us that we have x number of people in our group and we will be coming and going from the line...most people do not mind as long as they know what is going on and don't think you are trying to cut.
MJ