Alright a few bits of input here. First, congratulations........you made a working machine
Now for the useful stuff........
1) the cabinet design is pretty good, it looks a lot like a wooden Naomi (see attached pic), but you should take some notes from that design. Get rid of the shelf on the side and make the front a solid piece, it will look very slick.
2) You really don't need all of those controls. Frankenpanels are popular with some people, but they clutter up many otherwise great cabinets. Honestly, do you REALLY need 4 players, a flight stick etc? Go with 2 sticks, 7 buttons and a nice trackball (maybe a spinner).....you wont regret it.
3) Micro buttons a great for admins (if you want them). Midway cocktail start buttons are perfect. You can buy them for a couple of bucks from mikesarcade.com
4) Remount the monitor and case it in to match the cab. That will make it look more like a cab and less like a kiosk. You may even want to put flat panel speaker beside the monitor.
5) If you really want four players, consider a modular panel design or gamepad ports for players 3 and 4.
I hope some of this helps. Keep refining your style...it's unique!