If you only want to fly with Swiss on European routes, you can always find the cheapest price on swiss.com. Swiss is most often used on routes to Southern and Western Europe, but also has an extensive network in the Balkans.
Swiss operates many long-haul routes to all continents except Australia.
From Prague, direct flights take you to Zurich and Geneva, where fares are consistently at their lowest when departing from Prague. While you can also get a return ticket to Geneva under 110 eur, flights to Zurich are more expensive and hard to get under 165 eur.