So I'm clear: you have a collection of devices with switch-mode power supplies that can handle the global 100-240V power, and you want a surge suppressor that will protect you on any voltage.
Since your power supplies can handle up to 240V, you just need a surge suppressor that handles spikes above 240V. So buy a 240V-rated surge suppressor, and use a 120V plug adapter for countries with lower voltage. Since your devices already handle up to 240V, then they can handle minor over-voltages on 120V systems just fine. Bigger spikes, like lightning, are going to be high over-voltages regardless of the base voltage.
I'm not sure of your solution if you have devices that have only-120V or only-240V power supplies, and you need a surge suppressor that can protect both. Buy new wide-band power supplies or build your own (it's not that hard).