Skyrim and fallout to see performance comparisons to the Vive/rift.
The lab to see how well games designed for current hardware translate to higher resolution. Also the photometry section in the lab will show a good example of how that looks on the 8k.
Something less demanding like beat saber so they can see how high they can push SS and what difference that makes to visual quality, it may not be worth it.
Serious Sam 3 to see the difference of Dx12 Vs Vulkan.
Budget cuts to see how a game designed from the ground up for current hardware translates into your wider Fov.