1. One of the great things about Southwest Airlines (SWA) is that there is no charge to change a reservation, or more precisely, to cancel one reservation and book another one. This is true even if the re-booking is for the same flight(s) as the original booking. So, after you book but before you fly, it can pay to check on whether the price of your intended flight has been lowered, e.g., if a sale has been launched after your original booking. And here's a really cool thing: If there has been a price drop, before going through the rigmarole of canceling and re-booking, call SWA and ask for the equivalent price reduction refund. Usually, SWA will give it to you. Lastly, SWA does everything it can to avoid having its prices tracked by third-parties, going so far as to shut down one website that tried and denying access to its prices on Google flights and such.
2. If you're flying cross-country on SWA, here is a nifty way to virtually assure your getting an Exit Row seat or, if not, the best next seat(s) available: Instead of booking a non-stop flight, book a direct flight, i.e., a flight with one stop but no change of planes. Then, when the plane stops at the intermediary airport, do not get off the plane, and move to the best seat you can find.
[Note: Many people use the terms "non-stop flight" and "direct flight" as if they were synonyms. They are not. "Non-stop flights" have NO stops between your point of embarkation and your point of disembarkation. "Direct flights" have at least one stop and could have more between your point of embarkation and your point of disembarkation, but there is no change of planes required.]