I'll play, but I like doing weird things that somehow still make sense.
Narrow side 1 - the Shmup side: a dedicated shmup joystick (with short throw and engage) on the left, 3 action buttons, and I don't really want to, but I would end up adding a 4-way leaf joystick in between them for original cocktail games that flip the screen on the basis that building a cocktail cabinet that couldn't play original cocktail cabinet games would be wrong. A better approach might be to use a single Suzo 500 (which is a good shmup stick) and add a mechanism to rotate the base to switch between 4 and 8-way.
Narrow side 2 - the old school side: spinner, dedicated 4-way leaf joystick, 2 leaf buttons. You could add a Tron stick on the right. I wouldn't, but you could. If so, make that spinner a hi/lo one.
Long side 1 - The 2 player Neo Geo/Street Fighter side: Happ Supers, straight 6 button layout (concave buttons), no 7th button. If there is room, I'd squeeze the trackball into this side to play The Irritating Maze. If you want to get crazy add another for player 2 for Marble Madness and a few other games I don't remember.
Long side 2 - two 360 degree steering wheels, one button each, and pedals for playing games like Super Sprint and Super Off Road. Add a shifter in between and use the left wheel to play the rest of the 360 degree wheel games. You may be tempted to add a flight stick, but all flight stick games suck. If you do add a flight stick, make sure it's analog.
By not having trackballs on the end, you'll miss out on Atari football and Centipede, but they are not worth it IMO. You could still play Centipede from the side, but the vertical image on the horizontal screen will be small.
EDIT: on the driving side, I'll add that switch pedals work fine for the games I mentioned, but you'll need analog ones for games like Pole Position and Outrun. Also Outrun didn't use a 360 degree wheel so requires modifying MAME to make it play correctly with one.