I go to Croatia every year bcs I have relatives there (seaside). Coast is stunning, north part is called Istria, mid part is Kvarner, and south part of coast is called Dalmatia. In Dalmatia a-must-see is Dubrovnik, Split, Sibenik, Zadar, and you should see at least 1 island there. Island of Hvar is beautiful, it is a sort of creme de la creme of all islands, all world's jet set is visiting Hvar with their yachts in summertime. Hotel Riva is great place to stay, quite expensive though. Island Korcula is sooooo beautiful. You shouldn't miss islands Kornati. I've been there on a cruise & had great time there. As jajjay77 wrote the sea food is delicious. Also visit Plitvice Lakes National Park, nature there is amazing, so special!
Beautiful places in mid part of Croatian seaside are Rijeka (the old part of town), Opatija, island Krk which is connected to the mainland by a bridge. There are few interesting places like as Baska (my fav), Vrbnik (very old part of island Krk), Klimno (healing mud beach) ....
In Istria which is the northest part of Croatia and worth to visit are Rovinj, Umag, Pula with it's own Roman theatre and that's about it.
About the attitude toward foreign tourists don't worry, hospitality is on decent level. They don't have EURO, so it is a little bit cheaper than Italy, not much though. Especially in summer season! The best way to travel around / along the coast is by car. Old city centres are pedestrian zones. Buy
homemade olive oil, it's the best in the world. Expensive, but quality & yummy.
Ofc visit also Zagreb, the capital of Croatia. I hope these infos helped & don't forget to have a great time!