I didn't want a cp wider than the cabinet either, so I had the same problem as you although I'm using a 22" widescreen LCD monitor.
The cp is 660mm wide (26") I think this is just about adequet width for 2 players but I think it would start to get a bit cramped if any smaller.(I'm going to fit a spinner instead of a trackball)
The border around the monitor is 3 3/4" thick which isn't too bad but I wouldnt want it any bigger.
I think I got the balance about right. You can't have it exactly the way you want it unless you get a larger monitor which starts to get expensive.