Maria's place is basic and perfect. More than enough room for two people. The air conditioners work great and the shower is nice and hot. The balcony is private if you want to do some sunbathing and she has an umbrella with chairs down on the beach which is a 5 minute walk away. If you are worried that you will miss out on the sunsets over the caldera don't be. Rent an ATV and drive the 20 minutes it takes to get to Fira or the lighthouse at the southern end of the island. If you absolutely have to go to Oia, and you do at least once, it is a 40 minute drive. You can get to all the big sites- Ancient Thira, Akrotiri, Perissa, Red Beach, easily on the ATV.
Kamari has a great boardwalk with 20+ restaurants so you really do not need to go anywhere to eat. Go to Souvlaki Stop for 2.5 euro gyros and save money while getting a good lunch.