Krk is nice, and can be reaced from Rijeka by car (or public bus) using a bridge. So no need to take a ferry.
Baška , at the south end of Krk, has a nice, very long beach. Baska has some hotels, apartments, rooms (B&B), see Baska tourist board . There are also two camping sites, where you can rent bungalows or mobile homes. Camp Zablacé is next to the big beach (and you have to wear clothes). Camp Bunculuka is a very nice naturist camping with it's own beautiful nudist beach.
You mentioned views and sunsets: Just be aware that in many parts of (northern) mainland Croatia, and also in Krk, you never have a view of the wide open sea, and the sun hardly ever sets "into the sea", because there are many big islands "in front" of the coastline. So you see some water, but then you see land again. If you want to see the open sea, you need to go either on some western-most island, or to the south of the coast, near Dubrovnik. (Or maybe you find a good spot by chance or by systematically checking maps.)
In general, there are only a few sandy beaches in Croatia. Most beaches are with pebbles or rocks. But as a side effect of this, the water is extremely clear and the beaches are very clean (if humans don't leave garbage behind, that is.) I really was amazed when I visited last autumn.
There are overnight bus connections from (Bern, Basel, St. Gallen) via Zurich, Luzern to Rijeka, Zadar, Sibenik, Split, see www.expressbus.ch Online ticket booking probably doesn't work; it's best to just call them by phone.
Hope that helps - good luck and enjoy your holidays!