Hi, got 4 flights on US this week, with 4 of us in the itinary. If I look to choose seats, all I see left on most flights, is odd seats, exit rows and the 'choice' seats, are these likely to open up at the airport? I don't really want us all dotted around for 5 hour+ flights? Also one one of the flights, there are NO seats except exit and choice seats, will we get these at the airport, or should I start worrying?

Any help appreciated!