In my experience, U.S. obituaries seldom list attendees, at least not exactly. But they typically do list pallbearers, and sometimes they list "honorary pallbearers".
For me the best evidence that comes from obituaries is usually family relationships - parents, spouses, children, and grandchildren. Sometimes they will list special friends, special cousins that the person might have been raised with, special aunt and uncles the person might have been raised by, etc.. And obituaries usually give a date and place of death, date and place of the funeral, date and place of the burial. Sometimes but much less often they give date and place of birth, date and place of marriage, etc.
Family relationships in obituaries can sometimes require careful interpretation. Children of spouses are often listed as children of the deceased. This can be more or less appropriate if the deceased adopted or otherwise helped to raise the children. But sometimes children of spouses are listed as children of the deceased if the deceased and his or her current spouse were widow and widower when they were married in their 70's. And the interpretation of family relationships can require especially careful interpretation with heavily blended families that come about due to divorces or deaths of spouses.
The genealogical value of U.S. obituaries has tended to increase through the years. They are paid for by the family, and newspapers charge by the word. So early obituaries were often very short, announcing only the death and the funeral arrangements so that people knew when and where to attend the funeral. Modern obituaries are much longer and usually provide much more information about family relationships and the person's life history.