I bought couple of old photos on flea market that are more than 100 years old. Guy who sold them to me for small money did not had anything with those photos.

You can give bunch of your prints to some guys for free on flea market - let them circulate - they will be going from place to place long after you are gone

About negatives: if you don't have kids - maybe some other relative, or some kids from friends, or something...