To be specific Old Perithia. You'll find many ancient buildings and you are able to kind of replay how the greeks used to life there. It is a small venetian village and has a lot of charm! The ride can be a bit bumpy at times but it is worth it! You'll also have a great view over the hills and the people in the town are very polite!
Beachwise was Kassiopi my favourite beach along with Paleokastritsa! It was soooo beautiful, the water so blue and the white stones made a perfect scenery. But not only the beach in Kassiopi is great, also the town itself. Definitely take a stroll if you are there and make sure to visit the castle of Kassiopi!
To be honest Sidari is not that pretty in low season since it is pretty much abandoned and the beach was kind of dirty when we were there. But I am pretty sure, also what I saw from other pictures, that in high season the beach is cleaned up. Also the promenade is really nice with many restaurants and ice cream spots!