If you are planning to fly to europe in Spring 2012 (Jan-April), I recently stumbled upon a great airfare deal through Swiss Airlines via vayama.com (you cannot get this deal at Swiss airlines.com, you must use vayama.com). I was able to purchase a round-trip flight from the Western United States to Zurich, Switzerland in March for $572 r/t, with only one layover each way. This is a VERY good deal! Although my travel plans in europe did not initially include Switzerland (Netherlands and Germany were my main focus), I found that the savings from flying into Zurich (as opposed to Amsterdam, Brussels, or Frankfurt—-the other major flight cities in the region), were well worth the extra leg in the trip (savings of over $300). Also, Zurich is not far from some stops in Germany I was planning on, and it is supposed to be quite a beautiful city, so of course I do not mind staying here for a day or two!
Also, I found that using the “Buzz” feature on Kayak.com is very helpful if you have flexible travel plans and are looking for the best bang for you buck flight deal. It scans various flight deals for all cities in Europe (or you can focus it to a certain city or country) and for entire month-long spans. (Note: this is initially how I found the Swiss airlines deal on vayama.com!)
Zürich, Bruges, Groningen, Berlin, Kassel, Frankfurt, Zürich