We have hired a car for the odd day. Drive down to paleokastritsa, the drive down to the town is breath-taking. We preferred the harbour side to the beach side, it was a bit crowded. A visit to Aghios George (not sure how it is spelt but it is the next bay south from arilla) is well worth it. The sea here can be cold & rocky & slippy undefooot which makes getting in & out of the water fun! We call it Ag georgious.
Then you could head north, we tend to dip in & out of coastal towns.
We also drove ourselves to aqualand last year which makes a change form sea & sand. great fun if you're into huge water slides.
Hope this helps.
Karen