Fortunately, myself and the friends I play with are old enough to have grown out of the "gay factor," but I understand the limitations it might place on the younger crowd

But anyway... I'm glad I built a 4 player panel. I do play some 4 player games occasionally... however, the reason that I'm glad that I have it is primarly because I can play 2 joystick games with another person.
Stuff like Assault, Vindicators, SmashTV, etc... that require 4 joysticks total. If I had it to do over... which I do, and next Spring I'll probably do something like this. I would make the panel more square and wider so that I can get 4 people in comfortably and have all the joysticks in with the same orientation (I made the mistake of canting the player 3 and 4's slightly... it makes 4 player bomberman an nightmare).
This means my next mame cab next Spring is going to be a podium style cab like the above pics.
In addition to that, a 2 player panel with some limited controls will be on the drawing board as well. If it's your first panel, you can do what I did to get a feel for what you're looking for...
I just cut out some basic wood, slapped on some supports and started drilling holes and then put in buttons and a joystick and wired it all up to see what it was about. It really helped me understand the joystick configuration process and it was cheap ( 1/4 sheet of MDF ) ...