[spudlyo]

People rebind it. I bind it to ^o.

  # put this in your .screenrc
  escape ^Oo

[lambda]

I always rebind it to ^z. Since I never need to put a process in the background (I just open a new screen instead) when running screen, it never bothers me that that combo is a bit harder to type.

[_mrc]

or if you never use toggle-input-method, maybe C-\

  escape ^\\