In analysis I've hardly found a need for any line decoration atoll. Those little filled-in diamonds tend to poke through the napkin.
For design it gets to be important to know about "ownership". If you fire a professor, do all the whiteboards go away? If your diagram is your only mode of communication with someone, you maybe oughtta go for that kind of detail. But if you're standing around talking and something like professors and whiteboards is pretty obvious, skip it.
Dependencies are interesting all by themselves to see how well decoupled things are and to eliminate cycles in packages. These are things you're likely to see in the code more readily than a diagram. I just made a script to take output from JDepend (free from Clarkware) and make input for Dot (free from Graphviz) so Dot can draw package dependency pictures. My "review the picture, change the code, regenerate the picture" cycle is just seconds. Because Eclipse makes it so easy to refactor, this is not something I'd spend a lot of time designing before I start.