We are really really upset about the 2 hour delay on the return flight from Savanna, which caused us to miss our connector from Chicago to Duluth. United put us up on squeaky, shaky cots in a hallway at the airport with 70 others. We heard loud announcements and reminders over the PA system all night, in a brightly light hallway, then were rousted out at 4 am so vendors and others could use the hallway. What a really rough, unpleasant experience. Wow. We landed in Duluth 12 hours after we were due here. Delays in Savanna were never explained to us, we were switched on planes, and we watched for 35 minutes waiting to refuel. We missed our connector by about 15 minutes. Bad news.