Highest value? There will be limiting factors to that. Basically, it has to be low enough that it can't be overcome spuriously by noise or external factors. I imagine 100K would be fine in most cases, but it would be best to check first.
Lowest value is dictated by acceptable waste current (lower values drain more power from Vcc to Gnd, and will eventually act as a short for extremely low resistance) and the ability of your trigger to overcome the pull-down.