The last couple weeks at work have been really busy. I work 3 12-hour third shifts on the weekends (temporarily), so I don't plan on getting anything done then. But I've also been asked to work 1 day during the week the last two weeks. I haven't felt that I was lucid enough to safely use power tools.
I went through NUMEROUS revisions and mock-ups before settling on this design [this was the 6th(!) version]. I also like leapinlew's recommendation to put the admin buttons off to the side - also if you can, separate the "exit" button from the rest so no one hits it in the middle of a game when trying to pause or something and wipes out a high score on Mr. Do! or something!!
Admin buttons? We don't need no stinkin' admin buttons!

My upright panel doesn't have any. I'm thinking about "cheating" on this one and adding a pause button hidden away on the underside of the CP.
I agree that that layout is the best for a standard 1-joystick, 3-button setup. The one thing that really throws things off is that with the trackball/spinner on the right, the buttons have to be usable with both left and right hands. I tried the 3-in-a-row layout and it mainly just looked boring. Many games don't use/rarely use the third button anyway. I definitely prefer to use my right hand for a trackball, so that nixed the idea of laying it out as Trackball--Joy--buttons.
The supports under the CP are the reason that the start buttons aren't on the far right like a real Midway cab. I'm thinking the top-left might be good since pressing both will probably exit back to the front-end. The odds of slipping off the joystick and hitting both are pretty minimal. I've also toyed with the idea of splitting them up to the top-left and top-right to minimize accidents, but I don't think that'll be very visually appealing.
The joystick choice is still a bit up in the air. It's a pet-peeve of mine that people say they're going to build a cabinet to accurately play Ms Pac-Man and then essentially build a Street Fighter II control panel to do it with.
Since I'll mainly be playing classics I don't want clicketty joysticks. Sure, they're responsive, but they're not accurate to play Galaga with and they're also really loud on a metal CP in my house. I LOVE the beat-up Wico 8-way leaf sticks that are on my upright. BUT...I would like to have a 4 to 8-way switchable stick. I'm really kicking myself that about a year ago I passed up a pair of Arch Rivals 49-ways for $15. That would have been a good option. I don't think I can justify the cost of a P360. It WILL have a ball-top whether it comes with it or is an after-market add-on.
Odds are it'll probably get something generic until I get the money together to buy what I really want. I have a pair of beat-up ultimates laying around that may serve this purpose. Despite my ideals, I want this thing to be playable within the next month too. I'll just have to be careful of finding a stick with the same mounting holes.
Did I mention my Control panels are probably going to be made entirely out of bent plexiglas? That's today's project. I'll post pics.