The design looks pretty tight. And I agree with yotsuya on a cool unique design. 
My only gripe is that the player 1 and player 2 appear to be a mirror of each other, but then not. Meaning, the outline of the red and blue area is a mirror, but the interior portion is not. This leads tot he two inner joysticks (closest to what I assume to be a track ball) are not centered/spaced "right". But, maybe that is intentional. See attached image. Also, that looks pretty wide, so you may not have space. But, you might consider moving the trackball down if you have space.
Thank you!
Yes, establishing symmetry was a challenge and something that in the end was sacrificed to some degree. For the record P1 second joystick is a minigrip flight stick from Ultimarc to allow player one to have a trigger stick. My original plan had player two also having dual joysticks but the need really wasn't there so I dropped it. I know this is a frankenpanel but I want to try to keep it as nice as possible.
You did hit right on one of my biggest aesthetic complaints though and I'm not sure how to easily resolve it. I think the panel is already too wide and I'm contemplating trying to narrow it (currently 48"). I actually did have a version where P1's "circles" were centered on the second joystick to create a mirror effect with P2 but then P4 looked out of place.
I could pull P2 over to the left more so it lines up with P1 Joy 2 but I'm afraid that could interfere with trackball use (I've partially mocked this up mounting on cardboard). If I try to pull P1 over to the left it starts to feel squished as well and loses symmetry with the buttons/primary joystick.
I am a bit leery about the trackball being above the joysticks as it seems most builds I look at have it parallel. I can say Golden Tee is NOT a concern as it won't even be in my game list (sorry to the many fans out there, I don't know anyone that plays the game). The tb will be used largely for Rampart and Marble Madness.
I think I'll open it up tonight if I have time and see if I can get P1 Joy 2 and P2 to line up a bit better.
PS: To any who care the "lines" hidden in each panel are stolen from the Tron artwork, a bit of a tribute on my part to what is one of my favorite cabinets.
PPS: the system will have chrome T-molding and be shaped similar to a Gauntlet cabinet (low ceilings in my basement and this design helps).