The answer depends on several questions:
Is there a natural way to split the paper? If chapter 1 uses algebra to show that the number of plimps equals the number of glops, chapter 2 uses complex analysis to count glops, and chapter 3 uses this to construct an improved database design, splitting seems possiblee. If you develop one idea over a long time and the reader builds up a general understanding of the topic, splitting looks bad.
Would different parts of the paper address different audiences? If your work is in area A, but has implications to area B, people from B might simply ignore a long paper dealing with stuff they don't understand and don't care about. In this case splitting would be good.
Have you other publications? A 60+ page paper in a serious journal makes a pretty good impression. People will take your smaller papers more seriously. If you have no smaller papers, the benefit of a big one is somewhat diminished. However, if people get the impression that you split papers to increase their numbers, your reputation is lost.
Where do you live? There are countries where the number of publications is seen as an objective measure of quality, there are countries where quality is determined in a formalized way, and there are countries where personal impression and reputation count.