I managed to avoid falling into the bad ending at the hospital after retrying it three or so times. I actually was on the right path of doubting that Namatame was the real killer from the get-go, but the options were too obtuse and I asked the wrong question mistakenly.
After I got past that roadbump, I guessed that it was Adachi once I was finally given an opportunity to do so, and lo and behold, I was right. I cleaned his clock pretty easily, and the final boss was just pure trial and error. The endgame during the winter was heartwarming, and the credits finally rolled. I was really satisfied with Persona 4, easily one of the best games I've ever played. The characters were great, the plot was solid(sort of), and the combat was easily some of the better JRPG combat I've seen, and although the dungeons were a step-up from Persona 3's, they were still fairly meh overall.
I went on the internet, eager to discuss my 65 hours of awesome, but I find...that I missed something pretty big. Worse, I had already begun my New Game + and my only save games aside from that all date back to early December
I know that I missed a dungeon after having talked to all of my S-Link friends; although I'm not sure how I was supposed to access it. I didn't complete the Aeon Arcana in time, so I know I missed out Marie's extra dungeon. I also never got the chance to go through the Jester Arcana either; was there also bonus content to go with it too?