Thank you all for your responses, it has been very helpful to see your various perspectives.
With this being my first attempt at a home NAS, it's more about just getting something up and running using equipment I already have on-hand. I'm hoping to train both myself and the rest of the family to utilize the NAS to backup our files. If our needs exceed my initial deployment, I'll certainly look into investing into a more expandable build.
Before this thread, I had not even considered a NAS specific case, I was just stuck thinking about a standard ITX or mATX case, so I'll certainly look into that, as well as swapping out my CPU cooler for something more low-profile. While I'm at it, I'll likely pick up a smaller SSD as well.
Thank you all for your input, I appreciate it!