I'm going to have many panels, my goal is to have no redundant buttons on any single panel. I guess it's a bit of an opposite extreme from my 40" wide 4-player/trackball/4-way/8-way firetop/spinner panel I just retired. I find, since I've started collecting dedicated games recently, that less can be more. When I have people over, I want to just set my MAME up on 1 game for the whole night, which means less time messing around with changing games, telling people what button does what, etc. It was an eye-opener when people tended to play my Turbo game more than my MAME, mostly because for anyone who's not into it, a frankenMAME is very intimidating to walk up to and try to use. Having only the relevant controls available on any given game will make it much more approachable I think.
Right now I have 2 panels built, a Tron panel (with an original stick... Nice!) and a 4-way 2-button panel (using the GGG leaf buttons, man those things are awesome). So far the only game I've played that actually uses both buttons is Qix, but on the single-button games like DK, etc, I just programmed both buttons to jump.
I think I'll go forward and commit my 2 Wico leaf sticks to this panel. Even if it's only used for Robotron, I guess I love that game enough to make it worth such nice controls. Some of the other games mentioned look pretty good too. Also, I think Tapper will be playable with this setup as well.
Thanks for the suggestions!
Ryan