I mostly want to retire a big party of adventurers of all races in a dwarf fortress, and then play that fortress. It seems like almost all adventurers retired in a player fortress become hostile.

I had a conversation with some other forum goers about this here:
http://www.bay12forums.com/smf/index.php?topic=141123.0

and it seems like the only way to have an adventurer not be hostile when you unretire the fort is if that adventurer was generated with a background coming from that exact fort.

I've slightly modified the save so that dwarves, elves and goblins could be outsiders (thus removing any conflicting affiliations).