I love Southwest Airlines for a number of reasons. They outperform every other airline I have traveled on except for maybe Frontier or other small specialty jet companies.
One of the reasons is because I like being able to determine my own seat. My preferences change depending on the day and flight, so having that option is great. For instance if I am flying from Nashville to, let’s say, Chicago in the early morning, I will find a window seat on the left side of the aircraft. First, since I prefer window seats and second because the sun will blind me rising into the sky from the east on the right side of the plane. Making that adjustment also helps with being able to see the ground better on a clear day and I enjoy looking out onto the world.
So if you fly Southwest and like window seats, think about where the sun is in the sky in relation to the direction you’ll by flying. Also consider this if you are booking flights and pre-selecting reserved seats on other airlines too.
I might add regarding Southwest, it is also nice to be able to change seats in an instant if someone loud (or potentially annoying) sits down close by.