My latest Platinum is also from LEGO Batman 2: DC Super Heroes, which I picked up over the Summer. This has to be the fastest time I've Platinumed a LEGO game. By comparison, it took me about a month getting through the Harry Potters. Of course, there you have to sort of know your way around the castle and check every single room and check it all over again just to see where and if you've missed out on a puzzle.
Sonic Generations. I got 3 trophies in a row and had to get one more. The last was a silver trophy in which I had to defeat the last boss without getting hit. This trophy alone took me 2-3 hours to get. To be honest, the last boss battle for Sonic Generations is one of the most unfair and worst levels in the game.