Hello fellow Canuck! Others have answered your question about the Smithsonian Museums and other sites, but regarding the White House. The White House website says foreigners should go through their embassy to book tours, but the Canadian mission recently posted a clarification, essentially saying “We don’t know what they’re talking about.”

The only times when I as a Canadian was able to tour the White House (generally just the East Wing) was through friends or colleagues who interned there or knew someone who worked there. And even then it’s been a few years so not sure if that’s still possible.