AliasBot
Explorer
My first thought with the Underdark subspecies was to give them blindsight 60' rather than super-darkvision, playing on how real-life animals that live in isolated cave systems (or just purely underground in general) sometimes go beyond "underdeveloped eyesight" to being out-and-out blind. But I think that would mean that they could ignore their Sunlight Sensitivity by just...keeping their eyes closed? And as much as I personally don't care for Sunlight Sensitivity, it seems like a trait that's pretty important to the peoples that have it, and having an innate trait that counteracts that weakness with no effort required, especially in a way that's that silly, is probably a bad idea. So that might be a dead end.
Aarakocra should have some sort of enhanced vision - that could be the basic "advantage on Perception rolls relying on eyesight" Keen Sight that Eagles and Owls get, or it could be something more like the "can see a mile away in perfect detail" vision that Eagle Totem Barbs get, but they should definitely get something. That might end up stepping on what people want to do with Elves' sight a bit, but I feel like eagle vision is a reasonable justification for Aarakocra to play in that space, too.
Aasimar can innately cast Light, so they have no need for darkvision: why skulk around in the darkness when you can bathe the world in holy light?
(The real spicy vision mechanic for Aasimar would be to give them 5-10' or so of truesight - a bunch of Celestials have truesight, so a highly-restricted version of that effect feels right for a people with celestial blood. Would truesight break anything in the early-game badly enough to take it off the table as an option?)
Aarakocra should have some sort of enhanced vision - that could be the basic "advantage on Perception rolls relying on eyesight" Keen Sight that Eagles and Owls get, or it could be something more like the "can see a mile away in perfect detail" vision that Eagle Totem Barbs get, but they should definitely get something. That might end up stepping on what people want to do with Elves' sight a bit, but I feel like eagle vision is a reasonable justification for Aarakocra to play in that space, too.
Aasimar can innately cast Light, so they have no need for darkvision: why skulk around in the darkness when you can bathe the world in holy light?
(The real spicy vision mechanic for Aasimar would be to give them 5-10' or so of truesight - a bunch of Celestials have truesight, so a highly-restricted version of that effect feels right for a people with celestial blood. Would truesight break anything in the early-game badly enough to take it off the table as an option?)