First off, awesome news luulu. Have fun! Second, I fly Southwest all the time. Some people are put off by the "cattle call" but after years of flying, I feel the benefits of flying SW far outweigh that one negative (best customer service, not only for an airline but for any business). You don't get assigned seating, you get a number according to the time you checked in. B17 basically means you'll be the 77th person to board the flight and find a seat, after they'be loaded A1-A60. A1-A15 is for people who've bought the early bird. I'm not sure if this is still accurate, but I believe families with small children are let onto the plane right after the early birds, specifically so they aren't separated. Yes, it's crucial to call exactly 24 hours ahead on the dot, and even doing that doesn't guarantee you a good seat. For some reason, my wife is a pro at it and can always get us in the area of A1-A30.