I have always flown SW, but I have been blessed enough to have children with me that are under the age of 5, at least 2 are. But we just returned from Tampa, and I believe that SW said those traveling with children under the age of 4. Which I had 2 of. We were able to all get on together, but I have heard that SW will separate Mom and Dad's so that kids 4 and under can get on with one parent while the other members of their family wait in either A, B, or C lines. Now, I have not experienced this and I travel on SW with dh and the boys at least 2x a year, but I also read that this is when traveling to Orlando, MCO, which we have not done yet, we only go to Tampa (my parents live over that way). You can print your boarding pass online at 12:01am on the day you fly, but then you still need to get there early enough to stand in line, under A, B or C.