Peter,
At this point you should see iCal and Address Book as repositories for data that meets a universal standard (vCal and vCard) that allows the data to be shared and interacted with other apps in a predictable manner. Apple had chosen (thus far) to put together very simple and limited applications to access that data. Address Book is more useful than iCal IMHO. With that in mind, ultimately you'll want a PIM that live syncs with the iCal and Address Book data. As of right now, no one has a PIM that does this completely. Given that, here are some suggestions:
Palm Desktop for Mac gives you all the same (though implemented differently) functions you mentioned above, and all is very well integrated within Palm. However, there is no integration with iCal or Address Book and it doesn't look like Palm is going to improve Palm DeskTop for Mac. Many of us wish they would but Palm seems to be having bigger problems to deal with. You can however export (and import) vCal and vCard data and export everything else. If Palm worked for you before, it might be the right (free) solution for you now, at least until someone else comes out with something better. (And it might even import your old data).
Chronos developed something that was very close to Palm Desktop (and more) but they let it sit for years. The good news is they are coming out with a completely rewritten replacement (SOHO Organizer). StickyBrain is a good Chronos product and should give hints of things to come. But many of us are waiting...
OD4Contact offers some integration with iCal/Address Book but they have more work to do. They too have an update pending which hopefully will make more progress toward a complete PIM and integration.
JumSoft's Process and EconTechnologies' DayChaser are also options with a pending updates. These are both very good but still fall short; Jumsoft promises to tone down their interface.
LifeBalance works for some foks but it too needs some updating IMHO, but it works for a lot of folks. It is mostly a calendar program.
All that said, I use iCal, Address Book, StickyBrain and keep all my old data on Palm DeskTop for now. I expect Chronos' new product will meet my needs, integrating with iCal, Address Book and StickyBrain, as well as importing Palm data, hopefully leaving me with just one app to serve as a PIM. All this after an extensive search for the "right" tools (including OmniOutliner, NoteBook, NoteTaker, Devon, Nova, Inspiration, etc., etc.). I may also use either Merlin (by Project Wizards) or iTaskX for project management. Both of these have updates coming and my choice will largely depend on how well they "fit in" with the work flow and other apps.
Hope this helps.
DB