Sassnitz: on the island of Rügen (Ruegen), major fishing port with the longest outside mole of Europe, chalk-cliffs north of the town ("Königstuhl" => "Kings chair")
Peenemünde: on the island of Usedom, V1-museum, small motorcycle racing course
Rügen - Germany´s largest island in the Baltic just off the coast, location of many seaside resorts and scenic sea cliffs, great bathing beaches
Usedom - nice island in the east of Mecklenburg-Western Pomerania
Müritz - Germany´s second largest lake, with a national park on its eastern shore
"Vorpommersche Boddenlandschaft" ("Western Pomeranian Lagoons") National Park on the coast between Rostock and Rügen
Jasmund National Park on Rügen Island
In the larger cities (especially Rostock) you can get around well with English. Elsewhere, only younger people regularly understand English, so learning a few basic German phrases can be helpful.
Rostock airport (Laage, RLG) has few international flights, so the best choice are usually the airports of Berlin and Hamburg.
Trains from Hamburg and Berlin to the major cities (Rostock, Schwerin, Stralsund) leave every 1-2 hours. There are also regular train connections from Poland (Szczecin).
From Denmark (Gedser) there are frequent ferry connections to Rostock. Trelleborg in Sweden has several departures a day to Rostock and Sassnitz on Rügen Island. There are also ferry lines from several Eastern Baltic ports, primarily to Rostock.
The fast motorway network (Autobahn) has been considerably extended during the last years and all larger cities now have excellent connections. In the summer months, especially on weekends, the motorways and all roads to the coast can be congested.
The train network is well developed and even smaller towns have regular connections. Take some time though - a 50km ride can take an hour or more, which is considerably longer than elsewhere in Germany. Bus connections are usually only available when no concurring train service is present and many lines are infrequent. In rural areas, travelling by car is the most comfortable way to get around. The quality of the roads is generally very good. Locals often drive aggressively, disrespecting speed limits and overtaking recklessly.
A very interesting way to get around is by bicycle. There are special touristic bikeways along the Baltic coast and from Berlin to Rostock. Most regular roads also make attractive bike routes. Main roads often have separate bicycle lanes beside them. If they don't, keep off - riding there is both dangerous and unpleasant!
the hanseatic cities on the Baltic coast, namely Wismar, Stralsund, Rostock and Greifswald are well worth a visit.
the 118 m chalk cliff "Königstuhl" ("Kings chair") on the island Rügen
the 5 km long KdF-building complex and ruins in Prora on the east coast of Rügen (KdF = "Kraft durch Freude" => "Strength By Joy"): Not pretty, but impressive
the Kap Arkona (Cape Arkona) on the north coast of Rügen
the beautiful sea bridges of some coastal towns (e.g. Sellin / Rügen Island and Ahlbeck / Usedom Island)
fish in all variations ("Rollmops", "Bismarckhering"...)
beer from the local breweries in Rostock, Stralsund and Lübz