The weather is pretty nice at the moment.
The ExplorOtorium is at the waterfront at Pier 17 Is always worth a visit. If you can make it to the warf, check out the Musee Mechanic at Pier 45. Forget the other one which is way too touristy. 39 as I recall.
The vintage stuff is well picked over.
Chinatown often has interesting stuff. There are vintage streetcars and subways which go everywhere.