After doing a reasonable amount of research into the monitor options and asking a question here, I finally decided on a monitor to use. The original idea to use the Apple monitor would have left me with a bit of a smaller sized screen, so I started looking into monitors that were slightly larger screen but RGB and Sync compatible. I finally decided on a Sony PVM-14N6U. This is a 14" screen, just over 13" viewable, has composite and RGB/Sync inputs and will suit the purpose fine.
I hope to start acquiring parts soon so I can do more design work. I have some rough sketches but since I haven't any parts on hand I can't draw it to scale as of yet. I'm mostly sketching out my ideas. I know I'll be using a Neo Geo single slot, horizontal orientation arcade board like Ben used. Probably an MV1A, I've been eyeballing one but can't spring for the purchase yet. I'm still not sure if I'll be using a PC power supply or a real arcade power supply. I don't seem to have a spare PC power supply lying around anymore, perhaps I need to dig further into storage...thought I had one 
. If I end up having to buy a power supply, might as well get a Happ arcade power supply while I'm getting all my Happ joysticks and buttons. The best Neo Geo compatible JAMMA harness I've found so far is from "The Real Bob Roberts".
The design of the machine will be two player, but designed as such that I have a removable single player control panel. Behind this panel will be 15 pin D-sub connectors for one and two player control boxes. You can have the machine set up as a single player unit on your tabletop. Then, when you want two player compatibility remove the control panel (likely some form of tool free disconnect like a tool box latch), slide it over, place the player 2 control panel beside it and hook it into the 2nd D-sub connector. I'm making a 2nd panel because as narrow as the machine is going to be, 2 players on one control panel would be kind of close together. I'm making both panels removable for easier transport, even though I could leave player 1 hard wired. The machine will be capable of free play or coin-op with a double coin mech. over-under style coin door beside the monitor chassis and a small coin box beneath.
Overall, my build will end up slightly larger and heavier than what benheck did but it will be fully 2 player free play and coin compatible and should still be very portable. Especially compared to a full sized arcade machine. I hope to begin sourcing parts soon and doing more rough drawings to get my ideas on paper as well as some basic computer aided design work in graphics programs. I don't have access to all the fancy design software, but I'm sure I can make due. The biggest adventure for me will actually be the cabinet building as I've done little wood working and I hope I can produce a decent looking result. I can borrow dad's table saw for the large rough cuts, but I may need to get a jigsaw if he doesn't have one...I can't recall. I will be buying a router as I plan on cutting a groove for T-molding in my cabinet and I may use it for other things in the future. The electronic wiring part of the build should be no issue.