Arthur, four - not three - budget airlines to Europe
Arthur Frommer lists three airlines that fly you to Europe on the cheap (in his lead article on the home page this week, Nov. 2016). In addition to WOW, Norwegian, and the Toronto-based Canadian carrier he mentions, I would add Icelandic - flew them recently and saved a lot of money. Just like WOW, all their flights stop over in Reykijavik for a short hour or two - no big deal, actually quite nice to stretch legs etc. From there it is only another three hours to, say, Paris.
ADDITION: It's now almost Christmas and I'm using the "EDIT" feature to add one more airline that should have been mentioned in this context but wasn't:
TRANSAT. Both TRANSAT and WESTJET are budget airlines that fly inexpensive routes between Canada and Europe, and if you can easily access their departure points from the US, you could benefit. A friend of mine lives in Seattle and takes the train up to Vancouver to fly to the UK...