New Racial Senses

Simply put, giving every single Dungeons & Dragons race either Darkvision or no special senses is boring and lazy. To remedy that, here are some suggestions for supernatural senses that replace Darkvision (and sometimes replace a little more than just Darkvision) in most of the races that would normally get Darkvision.

Now, Darkvision by itself is not terribly boring or bad (only it's overbearing prevalence is) so it would make sense if some race would get to keep their Darkvision. I've arbitrarily decided for that race to be Gnomes. This also helps Darkvision itself feel more rare and special.

Dwarven Senses

In addition to Darkvision being boring, Stonecunning is a really weird racial feature. With the way it works it doesn't make sense as something that every Dwarf knows from birth, it's far more like a skill you receive through your Dwarven upbringing (which not every Dwarf would necessarily get). To fix that, the following racial feature replaces both Darkvision and Stonecunning:

Stonesense. You can touch any stone surface with your bare skin and take an action to focus, gaining Tremorsense out to 30 feet. This sense is effectively blocked by any non-stone or non-solid surface (sand, dirt and gravel blocks it, for example). This lasts for as long as you keep touching stone with that same part of your body and for as long as you maintain concentration on Stonesense. Additionally, while Stonesense is in effect you have advantage on any rolls to detect secret or hidden doors, hatches or holes (such as traps set into the stone itself) in the same area AND can glean rudimentary information about the composition, quality and arrangement of rocks out to that range (this includes detecting structural instabilities or dangerously loose rocks).

Elven Senses

It's simple, Darkvision AND Keen Senses are boring. The following racial feature replaces both:

Sharp Ears. You have advantage on any Wisdom (Perception) or Intelligence (Investigation) checks involving your hearing and you can't be surprised by any creature within 5 feet of you as long as that creature makes any remotely audible sounds.

Half-elven Senses

Some might see this as a straight nerf to Half-elves but I disagree. Either way, if any race could do with an incidental nerf it'd be Half-elves, if only because it's vastly overpicked for players. Having what amounts to just a lesser version of the above racial feature just makes sense, too, so the following racial feature replaces Darkvision:

Keen Hearing. You have advantage on Wisdom (Perception) checks involving your hearing.

Half-Orc AND Orc Senses

I much fancy the idea of Orcs having some primal, hunt-enhancing supernatural scent over just being another Darkvision race. The following racial feature replaces Darkvision:

Blood Scent. You have advantage on any skill check involving your scent. If the source of the scent of blood (or any sharp, distinct smell) is within 90 feet of you, you immediately know the direction of that source, no roll required as long as nothing muddles the smell you are following (such as a strong wind or a myriad of other strong smells etc).

Tiefling Senses

Devils are a very interesting kind of monster, so deserves to feel and play special too. In addition to applying this feature to Tieflings, I would apply it across ALL Devils as well. So, the following racial feature replaces Darkvision:

Heat Vision. You can focus as an action and sense sources of heat, and the relative temperature of those sources, out to a range of 60 feet. You cannot sense any creature that is cold-blooded or unliving, unless it otherwise emits heat in some form but you can sense sources of heat through some barriers or walls but not through 1 foot of stone, 1 inch of common metal, a thin sheet of lead, or 3 feet of wood or dirt. Heat Vision requires that you maintain concentration and while maintaining concentration for it you are effectively blinded for purposes of detecting or being aware of anything not emitting heat.

Aasimar Senses

Angels, and divine beings in general, are very powerful beings. Which is why I think that giving a powerful supernatural sense to Aasimar makes sense, but it has to be properly balanced and hopefully this is a good take on it. The following racial feature replaces Darkvision:

Limited Truesight. You can focus as an action and gain Truesight out to a range of 30 feet. Limited Truesight lasts up to 1 minute and requires that you maintain concentration. When Limited Truesight ends, whether you stop your concentration willingly or it is interrupted, you suffer one level of exhaustion.

(A creature with Tremorsense can detect and pinpoint the origin of vibrations within a specific radius, provided that creature and the source of the vibrations are in contact with the same ground or substance. Tremorsense can't be used to detect flying, incorporeal or unmoving creatures.)

(A creature with Truesight can, out to a specific range, see in normal and magical darkness, see invisible creatures and objects, automatically detect visual illusions and succeed on saving throws against them, and perceives the original form of a shapechanger or a creature that is transformed by magic. Furthermore, the creature can see into the Ethereal Plane.)