Rügen has the Jasmund chalk cliffs, Cape Arkona and the resorts of Binz and Sellin, so more nature and more variety. Usedom offers the imperial spa towns, long piers, a promenade that continues to Świnoujście in Poland and the Peenemünde museum. Both are reachable by train.
No. Park at the large Hagen lot and take shuttle bus 19, or walk about 3 kilometers through the forest. Bus 23 runs from Sassnitz to the Königsstuhl, and the cliff-top trail from Sassnitz is about 8 kilometers (5 miles).
Long-distance trains serve Rostock, Stralsund and Ostseebad Binz. Warnemünde is on the S-Bahn, and Usedom is served by the Usedomer Bäderbahn from Züssow. The Deutschland-Ticket is valid on regional trains.
The Ozeaneum and the Maritime Museum in Stralsund, Schwerin Castle, the Peenemünde Historical Technical Museum and the exhibition at the Königsstuhl national park center. In Sellin, a diving gondola takes you below the water's surface.
Shallow beaches in Binz and Warnemünde, the Königsstuhl skywalk, the Ozeaneum penguins, the Rasender Roland steam train and the tower climb at Granitz Hunting Lodge. Kids and teens under 18 get in free at Schwerin Castle and Granitz.
One full day covers the highlights of Rügen. A weekend is enough for Schwerin, Wismar, Warnemünde and Stralsund. Add at least one more day each for Usedom or the Müritz lakes.