Can you recommend a hotel for an overnight before morning flight to Chicago?
Ellen, I've flown out of Arlanda in the morning many times. However, I've never stayed at a hotel at Arlanda. I've always just traveled to the airport in the morning from the city. The list of hotels is here. www.swedavia.com/arlanda/at-the-airport/service/hotel I'm guessing that you are taking the SAS flight to Chicago. If so, I think that leaves from T5 and is about a 5 minute walk from Sky City which is right on the airport grounds. There is a Radisson right in Sky City and this would be the most convenient. There are also a number of places with a shuttle service to the airport. Of these, I suspect that the Ibis would be the cheapest. You might want to check the tripadvisor reviews.
You can also get a hotel in Stockholm close to the central station and take the Alranda Express to the airport. It is the best airport express train I have ever experienced. Is super-fast, takes only 20 minutes, with frequent departures.
www.arlandaexpress.com