American and Delta offer $424 round trip tickets for Washington DCA to Munich for departures from April 15 to June 18. Icelandair has similar fares from Washington IAD with latest departure Sun June 25 at $431round trip. Icelandair allows stopover in Reykjavik for about $15 more.
Delta Airlines Washington DCA – Detroit DTW – Munich MUC – DTW – DCA
Icelandair Washington IAD – Reykjavik KEF – Munich MUC – KEF – IAD
American Airlines Washington DCA – New York JFK – London LHR – Munich MUC – London LHR – Philadelphia PHL – DCA