I stayed at Stefania and Salva's place for four days but I guess two/three will do.
First things first, host-guest communication and care are top notch.
Second, the apartment is great - the terrace and the outdoor kitchen are both amazing. The living room with the vinyl record player will make your evenings a blast!
The bedroom bed is very comfortable and the internet works great!
The only drawback I experienced was water pressure in the bathroom (it felt just like a drizzle when you were taking a shower). The host made it a little better though.
And now about Siracusa, as hosts suggested it should be one of your highlights to go explore Archimedes' temple site plus the Greek Theater. I actually went there past its opening time but I saw most of it from the outside of the fence. They close at 3pm!
The views in Ortigia are breathtaking! Since I'm a sweet lover, I strongly recommend Viola bakery for sweets and ice cream!
And about the area, don't miss Noto!:)