Level 60 is plenty! I finished the game at level 64. Just finishing the Pharos Tower will probably get you to 64, it is huge....

Yeah, like you said, I missed the interactions between party members. Part of it is no in battle banter, I just loved the little quips from Rikku and Wakka in X and X-2. Part of it was just plain lack of camaraderie. It's like your party is in the same subway car, they barely talk and most of the talk is mission related or some deep dark personal anguish that gets completely forgotten after that single talk (Van's brother, Balthier's problems with his dad). The game just rushed past all that towards "The fate of Dalmasca".