I’m no experienced Simmer by any stretch of the imagination. But I did want to answer your question as to what I do. All my deceased Sims graves go to a custom graveyard that I built. It’s very basic with sidewalks, benches, street lights, trees and other decorations. Since it’s a legacy family, they are all related. In TS2 where I’m playing many different families, I create sections for each family. I’ll do that in TS3 when I stop playing this family.
As for diplomas and awards, I create a large office to put up those special things. The more wealthy my family becomes, the larger the office becomes so more wall space.