On the Murata OKR-T/10, the data sheet specifies a 49kohm pulldown resistor but I've seen people using a 1k. Is there a more correct value or does anything 1k or above work just as well?
Here's what the data sheet says: -
The 49kohm is the internal resistance of the circuit, not an external resistor that has to be supplied - note the circuit diagram is suggesting a switch open or closed because that's the simple way to show it but resistors will do. Just don't go too large.
Also note the error in the specification - the picture says "open = on" and "closed = off" whereas the data in the table is implying the opposite - it says "OFF = open pin" but that is probably a typo.