On Mar 19, 2012, at 12:57 PM, Stefan Monnier wrote:

Assuming you manage to get the "reuse frame when possible" to be the
default behavior, than -c will still let the user choose to force
creation of a new frame.

I didn't think of that. I like it, that's the way I'll implement it.

  emacsclient --display "$DISPLAY" <file>

On my machine (Mac OS X) that always creates a tty frame.