Reddit mentions of Undaunted Courage: Meriwether Lewis, Thomas Jefferson and the Opening of the American West: Meriwether Lewis Thomas Jefferson and the Opening

Great! I'm happy you like the book suggestion; if you are a book person you should love it. Just don't hate me when you get to the... porridge part. Only the first book really takes place in Sweden (in the others they've crossed into America), so from a strict preparation perspective you would only need to read that. But if you should happen to like the series and read it all, then know that it has been made into both a movie and a musical.

Since you seem interested in this kind of stuff, here's a few more readings you could do:

• One about vikings; this is much more loosely connected to reality, but it's a great and raucous tale and surely there's something about Swedish mentality in there.
  
  
• One that was actually comissioned to be a children's geography book; this will maybe feel a little dated, but if you read it with a map on your coffee-table you will get a colorful view of the land.
  
  
• One about poor, hardworking people in early industrial Stockholm. This is set some 50-75 years after The Emigrants, when Sweden is industrialising, and written in maybe something of the same "earthy epic" style. If you should like it then you can go on with a whole series. There are walks and sites for this in Stockholm as well.
  
  Do come back and talk to us when you know where the wedding is.
  
  And thanks for the US advice offer, though we've pretty much done our year of research on that. About half finished reading this by now. =)