If you want to see how others are doing 4 player panels, then check out some of our 4 player machines. You'll notice that we use 6 buttons for the centre players and 4 for the outer players for the same reason you mention about playing console games; 6 really is plenty for most games (even PS1 & N64 where many buttons originally weren't often used or could be remapped) and with the outer players, this is truer still as multiplayer games tend to be simpler still (most arcade games 2/3 will do, very few used 4, multiplayer console games rarely used more). With regards to the sticks, angled sticks have never been a problem for us, customers or show attendees so if you did decide that you'd be safe.
Our layout is obviously not for everyone's needs but obviously we have a lot of experience and feedback to work from so have decided our default layout covers most bases. Certain things like extra admin buttons are also normal for us and we use a coin button forceach player which obviously helps with console emulators, but they're a good reference point even if you don't have these features. The way we position our spinner and trackball is also worth noting as although they simply seem to be fitted in convenient spaces, the trackball position offers most space around it, and the spinner is placed so that the hand and arm rests in a space free of controls whether left or right handed.
For the best close-up pictures see our facebook page or YouTube videos.