Hmmmmm... How can I answer this...
Mario is a Nintendo Copyrighted character; that is, his games are only found on Nintendo systems... Thus, the only system of the 3 that would have ANY Mario games is the GameCube. Of course, Nintendo seems to be marketing to the ages of your kids...
Anyway, as for the husband... actually the XBox has better graphical capabilities than the PlayStation2... but the Playstation 2 has a much greater variety of games... not to mention an easier to handle controller... In actuality, the PS2 is likely the best choice for his gaming preferences...
Anyway, I can't really come up with a solution other than to get both (Maybe for Christmas? Sorry in advance if you don't celebrate Christmas) systems... problem there being that the systems combined will run you about $400 US... not to mention controllers, games, periphericals (That is, Memory cards and other accessories) Maintenance (Hey, you never know...) and other expeditures... It would be a rather expensive option... But, it is the only way I see to make anyone happy...
(I apologe in advance for my vague answer)