I'm personally more of a fan of Caldwell Airport opposed to Morristown Airport, Caldwell is more general aviation oriented whereas Morristown is jets. I love the location of KMMU, I think the runways are excellent, and the controllers are great to work with, but it's expensive to hangar/tie-down your plane. Caldwell is a very well taken care of field, I like the fact it's a little closer to everything, the controllers aren't that great since it's a teaching tower BUT I like Caldwell far more because there's more of an old school GA feel to it. Most of the time if I'm going to go for a flight I bump into other pilots, get a chance to socialize with other guys in the hobby. I also really like the school that I work with at Caldwell and that plays another roll in my decision, I know planes are accessible and competitively priced if I want to rent a Cessa opposed to flying my Diamond.
I got my PPL at CDW and currently fly out of MMU... both airports are fine and are GA-friendly (well, as friendly as they can be, near the big city) and pricey... feel free to ask any specific questions shall you have any.