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?
I would say that a 49kR is inside the chip and if you want to enable it you need to explicitly drive On/Off High (either by a transistor or a logic signal).
If you use a 1k resistor (pull-up) it will be always-on.
Don't forget input and output caps.
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.
FWIW I've never seen an 'E' version for sale, PN OKR-T/3-W12E-C, only the Standard version is available, PN OKR-T/3-W12-C.
I mention this because the answers seem based on the wrong version.