Some deconstructible bric-a-brac for the largely empty labs. For example, a Jacob’s ladder, a mainframe console, panel of servers, chemical vent hood, eyewash station, emergency shower, et. all. A source of lots of scrap metal, power converters, amplifier circuits, antennas, and so on.
On the subject of labs, the desks in the warehouse rooms need some loot. I never bother to even enter the warehouse office because there’s nothing ever in there.
Since you have US flags already in the game, military bunkers, military outposts, and refugee centres should all have at least one.
More destructible salvage in general would be good: paintings which can be cut up for rags and planks, framed photos which can be disassembled for silver and paper, ashtrays which can be used as a bludgeoning weapon or smashed for ceramic shards, hargers (found in most closets) which can be cut up for wires, carpets (why are all houses hardwood flooring when carpeting is already a Thing in the game?), rugs (and bearskin rugs which can be cut up for hides), posters (of the funny, motivational, artistic, or promotional varieties) which can be cut up for paper or hung around your own base, and so on. Also, smashing walls in houses should have a chance of giving a small amount of copper wiring.