Those flights I bet if you didn't get a window assigned, you can ask for an open one when you're at the gate, or even switch on the plane if it's got a lot of empty seats. It's not like a ball game where the usher kicks you out if you moved to a better seat :~).
I think, I'll be in window seats to and from Dallas, and on the aisle to/from Dallas to Seattle:\, I'll switch if I can.
Becky