If I could mark an entry as "done with this" for purposes of the friends page, while still having it available via the journal (or an "everything" view) if I really wanted it

Approximately, anyway. The CommYou Summary View doesn't *quite* map to the LJ Friends page, although they're quite similar in practice. And the core notion of "ignore" is exactly "Don't keep notifying me; I'll go back and look manually if I care later"...