I would like to see an interaction between Elevator Callers and Pneumatic Doors. By selecting a new option in the Pneumatic Door, the door would be able to detect an adjacent Elevator Caller and open only when the elevator is at that floor.

There are some alternatives for these but they don't work very well:
-You can use redstone to power a nearby iron door. This has problems:
1.You usually call the elevator by pressing a button, due to the placement of the caller and the door, the door is also powered.
2. Problem mentioned above can be avoided by seperating the elevator caller and the door, and use redstone to power the
door from the caller. This just isn't possible in a 3x3 space which most players probably use.
3.You can use redstone modules on pressurized tubes to circumvent this problem. But to make this work in a 3x3 space, you
need at least 2 redstone modules per floor (tested this). This makes it hard to have more than 8 floors.
-You can simply make the elevator larger than 1x1, but then who uses elevators larger than 1x1 (at least I don't, elevators aren't cheap lol).

What I propose is a new option along with the current options in the Pneumatic Door gui. By selecting this option, the door can open only when the adjacent elevator is at that floor, bypassing excess redstone usage and problems. This might also be an incentive to use Pneumatic Doors, I mean I never used them.

This can already be done. The Elevator Caller will emit Redstone when the Elevator is at it's level. By placing it next to a Pneumatic Door Base, which can respond to Redstone signals, you can make it so the door will open/close as the elevator reaches/departs that level.

If you look on the right of the Pneumatic Door Base, there should be an option to transfer it's redstone signal to the door itself. When done, the Elevator Caller will emit a signal to the Door Base (as long as they are next to each other), which will then be transferred to the door itself. Just put your door in "Iron Door Mode" and it should work as expected. If the doors seem to be all open or all closed, just use the system and it will fix itself.

I have confirmed that this works for both a 1x1 elevator as well as a 3x3, but the 1x1 is quite compact so there's a little caveat with the button opening the door before the elevator gets there, should be solveable with clever placement or wireless redstone (the Universal Sensor can detect when a remote block is right clicked and emit a redstone pulse, for which this is a useful application). Although with max speed upgrades on all the doors and the elevator base, this isn't noticeable at all.