WAS airport is actully quite convenient to transit in.
WAS is much much smaller than FRA or LHR so no looooong walks from gate to gate. There were quite a few shops and restuarants to keep passengers busy and there are 2 *A lounges at both extreme ends of the terminal building.
The previous poster was right about the comment that it would not be worth to pay for European C class on LOT. I had a miles ticket....
Have you considered Austrian via VIE for your trip? They sometimes have good deals from the USA?