For the 220uF/250v capacitors, the peak current is around 1 amp and the peak voltage around 200v, so the resistor must be greater than 200 ohms to avoid damaging the capacitor. If the current were steady, that would be 200 watts dissipation which is unreasonable!
The current isn't steady, but to do an evaluation you'd have to know the thermal time constant of the resistor, which depends on the size and construction of the resistor. Plus you'd have constraints like how long to wait between discharges.
Perhaps we should look for a resistor that will survive even if the circuit is still accidentally powered. Let's say you want to use a 5-watt resistor; then since power equals voltage squared over resistance, the minimum resistance is 8000 ohms. The time constant RC is less than 2 seconds, so if you leave it connected for 10 seconds (5 time constants) the voltage will decay by a factor of 175 (e to the 5th power) - i.e. to a bit over a volt. 10K is probably easier to find.
For a 1 watt resistor, you'd need 40K and it would take 50 seconds to discharge. I'm not that patient, myself.
