The Island tour is a fantastic way of getting your bearings in regard to what there is to see and do, especially if you hire a Moped or car to do further exploring.
Unfortunately I wouldn't recommend the Etam tour which if you travel with Golden sun will be the one your recommended by the rep. The Tour guide didn't have a clue about the Island or greek history, so no use if you want more info about the gorgeous island of Kefalonia or Ithaka.
Ohhh and she also needs a bit of educating on what type of flags different countries have, as she openly admitted to not knowing what the St Georges flag was..... the rep was English. The trip was a bit like a 'carry on' movie!
The drivers of the coaches deserve a good tip though, those roads are a challenge for even a car.

Visited Ithaca on an Island coach tour (same Rep as the Keffalonia trip!!! see comment on Island tour)Beautiful island, can certainly see why the rich and famous visit there.
I would recommend visiting a FANTASTIC jewellers in Kioni, the jewellers has 2 massive Olive Oils Jars outside, go up the steps and soak in the atmosphere, admire the creativity and craftmanship.

A Brilliant bay/beach for snorkelling in, if you manage to survive the pebbles getting in and out of the sea.
Saw a Stone fish, Massive starfish, and lots of sea slugs. Well worth the effort. Beds and Umbrella cost 8 Euros

Oh a word of warning, there tends to be a freak wave that comes a long way up the shore and if your belongings are on the sea's edge your lose them when the wave comes in.

Felt the beach was overated, not great for snorkelling, even on a calm day you could feel the current pulling at you.

It also tended to be REALLY hot and bright, hotter and more intense than on other beaches due to the whitness of the beach and cliffes, so beware those that burn
Costs of 2 beds and Umbrella - 9 Euros! expensive but it does have showers, Eco friendly toilets, changing area and a well shaded and well stocked Beach Bar.