Edit - and back to the OP's point: Aasimar are also resistant to Necrotic so they'd do just fine in your Pits of Deadly Death.
Where it really paid off was with a pack of Shadows, activated Inner Radiance, putting them in bright light and giving them disadvantage, while taking half damage and doing Radiant damage they were vulnerable to (and she is a Bladelock, so she can swing her sword with Radiant).
I've used the Radiant resistance, but I used the Necrotic resistance more so far. She also has Dragonscarred feat so she is resistant to Fire too.

