I also was hesitant to try SWA because I like having my seats in advance....but we started flying them about 2 years ago and now it's always my first choice if possible. Their CS is amazing when compared to other airlines (and many other businesses for that matter) and their prices & other policies are great.
I have one example of that from today ~~ My DD was scheduled to fly BWI to Nashville this afternoon. There is severe weather in the area today - strong winds, thunderstorms, even the threat of tornadoes. So probably many delays at the airport this afternoon and evening. I called SW earlier today to see about the possibility of switching to a flight tomorrow. When the rep looked up the info she said that no flights had yet been delayed "because of weather"; her plane was delayed though (possibly because of another late arriving flight).
The agent changed her to a flight tomorrow morning
at no charge (if I'd done it on-line the price was $70 more than what I'd paid). She didn't even hesitate to do so - simply asked me what flight she'd prefer and thanked me for choosing SW
We always check in on-line & get our 'A' boarding passes ~ never have a problem getting good seats on the plane.
I think that'll be the case once you try SWA