Grandma's House in Oia has a perfect location. You are on a super cool street, full of boutiques, restaurants ( don't skip visiting Atlantis Book Store or Karma Restaurant near by), on the Famous side of Santorini, but yet, you can watch a sunset from a terrace of your home, you have a view of the sea, and you are 2 minutes away from a Tourist Information open 24/7, bus terminal, ATMs, stores etc. 7 min walk from a swimming pool and drink bar, 15 min away by taxi from a rocky black beach of Columbus, and a short walk from famous Almoudi Bay, just few hundred steps to descend, then climb, but what a view! Yet, that end of the street isn't loud. The only thing that we missed at first was the air conditioning, but once we opened the windows the house was fine.
The house itself is very charming, clean, and tastefully decorated and Rodanthe is a SUPER HOST! He is very easy to communicate, he will book everything for you, give you great suggestions and advise if you aren't sure about what to do. And the price is very reasonable, considering it is a prime location in Santorini.