My cab's gotten quite a bit of 2-player play on SF, Marvel, etc and it is not uncomfortable at all. Here is what I used on my upright cabinet,
www.oscarcontrols.com/unnamed. I originally planned my layout to include a trackball, but I didn't want the control panel too cluttered so the trackball got moved to a second control panel.
As built:

Original plan:

Here's the layout for a multi-williams control panel, which also is set up for dual play on Joust, and the joysticks are perfectly spaced for Robotron. However, the 11 3/4" between joysticks may be a bit close for 2-player fighter games. (click for larger pic)
