My wife and I are hoping to go to Eretz Yisroel for Shavuos (JFK-TLV or EWR-TLV if necessary). We would live to have a 24-48 hour stopover in Europe to do some sightseeing - probably via Amsterdam or Brussels, or possibly Venice - but when I search for tickets on Kayak I'm only given options with short layovers (<10 hours). If I want a longer layover they charge much more money to book it as a multi-city ticket. Is there a way - ideally online, or at least by calling an agent - to get a longer stopover without having to pay extra, and to research the various options? Thanks!