To solve the problem: 1) Create a partition that is of type bios boot (I believe it needs to be 2K) 2) Create a regular boot partition /boot (I recommend ext4 or 3) 3) Create your other partitions per normal.
The machine is a Thinkpad from the last couple of years. It definitely supports UEFI. I'd think it would have to be a very old machine to not support it at this point, or am I misunderstanding something?
I work professionally in IT and one reason I'm installing it is to better learn my way around Linux. RHEL is the most prominent distro in business so CentOS seems the place to start. There's no better way to learn than to keep burning my hand. :)
I did make sure I used a Thinkpad to maximize the chance of a successful, functional outcome with CentOS or any other distro or 'nix. AFAICT, Thinkpads are by far the most popular machines among the developers of the various 'nixes.
One advantage to CentOS, for me, is its stability. I don't want rapid upgrade cycles. I have no need for the latest and greatest; I'm not gaming; I don't even use Bluetooth. Vim and a web browser should work fine regardless of the distro.