Personally I want different style game play, the idea of LBP is to have all these different types of levels made by others, there's almost limitless levels that will come from that, so now instead of a focus on puzzle solving platforming, they should have a system that makes really difficult and fast platforming happen that could be a focus on timing based jumps and such. (They've done it in NSMB Wii and Splosion man)
Other alternative is adventure based platforming ALA Metroid, which may or may not fit but could work with 4 players well.
Not really sure what else I'd want other than maybe some more competitive ways to play instead of slapping your friend into a pit while you go hopping along 
MaxwellGT2000 - "Does the amount of times you beat it count towards how hardcore you are?"
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