ModNation Racers (surprised no one has plat it yet in the league) is going to be a fun platinum, and certainly a challenging one. The trophies for 250,000 Create XP and level 30 (you need a total of 500,000 XP across all modes) aren't too bad, but will certainly be a grind (there's a workaround, but it involves making like 9-10 users on your PS3 and it's still a good 15-20 hours if you use that method). The challenges in Career Mode are where it'll be tough, since they all require (well, all but the first one usually) you to do something specific AND get first place.