Living in Atlanta, I really don't have the opportunity to fly Southwest - I usually fly AirTrash and when necessary Dumpya (Oops... Delta). I don't like to fly as I'm a bit claustrophobic... and all airplanes are cramped cattle cars in my opinion. BUT - that being said, I did have to fly from Pittsburgh to Chicago recently and SW had the cheapest flight (of course). So after experiencing SW for the first time - I will definitely never fly them again. And if they change AirTrash to their ways, I will only have Dumpya left to fly.
I am a pooh-sized gal - and to say the seats were tight is an understatement. I have never had a problem on any airline before SW. I usually travel with one small carry-on and my purse -- I hate the folks that bring their largest luggage and then try to smash it into the overheads -- and SW has the smallest overheads I have ever seen on a plane. It was chaos getting everyone on board and their kitchen sinks stowed. I kept my carry-on under my seat, but I was the only one in my row that did that. Everyone else insisted on cramming their bags in the bins - and it took forever. Getting off the plane was just as chaotic. I waited quietly in my seat until over half the plane dug out their bags and de-planed before I even attempted to leave the plane. And even then - I got hit in the head by a gentleman removing his personal valet/kitchen sink from the bin.
Though I do hate flying - I choose AirTrash because they are always fairly on time (compared to Dumpya), have very few schedule changes, and can get folks on and off a plane orderly. Plus, they're not afraid to stop a passenger from bringing on their entire personal belongings and making them check their bags.
I travel several times a year for work and have had to deal with a few schedule changes - but when made several months prior to my trip - the changes always seem to change back to close to my original flight. Additionally, I've called AirTrash directly after a schedule change and spoken with an agent - and got a flight a little earlier than my original one.
So, don't despair - call AirTrash and see if they can accommodate you - believe me - they understand vacations at Disney!
Good luck - and have a great time!