Differential ADC input buffer
In the dual supply schematic, there's no reference for the input voltage. Just as a for-instance, if there's no reference to ground on the input side, then you could be sending in 1000V+1*sin(x) which would result in the op-amps being railed for the entire time. Once it's got a good reference, it will be just sin(x) and shouldn't be railed so long as the resistors are chosen well.

The single supply also has this issue. The input is AC coupled which is fine, but the only place current to go is into or out of the output of the op-amp. If you've already railed it, then it won't be able to move from the rail. 

You'll want both circuits to have some kind of path to ground so that when the signal is 0V input, it will level out to 0V output.

RT should be split into two resistors with GND sent to the middle of it. CM on the single supply should likely be connected to ground probably through a resistor.