As a fellow Nintendo expert, I gotta say N64 and GC are dead last in this department, because Mario 64 and Rogue Squadron set the bar way too high, and that Wii will blow everything out of the water because the bar was set way too low since nobody tried at the beginning.
I think the biggest jumps have always been the most successful systems. When a system is still getting games made for it regularly for 7-15 years, it gets the biggest gap from prettiest early games and prettiest later games. I think the biggest were NES, SNES, PS2, with Game Boy Color in the lead.












