I really like Southwest, but I've never flown them from coast to coast, only for short hops, with no stops. For that type of flight I think they do very well. For the longer hauls I'm sure they are just as reliable. The downside would be that they don't serve any type of meal, not even one you can purchase. If you're prepared for that and bring your own food on, you should be fine.
What the "cattle call" means is that there are no assigned seats. Passengers are boarded by groups - A, B or C. You can check in online and receive your boarding pass ahead of time. That is the best way to assure you're in the A group. If I'm flying alone I don't really care which group I'm in, unless I have a lot of carry on luggage that needs to be stowed.