There's a Greek national park just southwest of Thessaloniki, which is just across the bay from the international airport. It seems like there ought to be somewhere between Thessaloniki and Litochoro that can support multiple permanent athletics venues--with the obvious exception of the marathon, which would have to start in Marathon and end in Athens.

And if Sochi can do a Winter Games, so can a mountain resort in the Olympus Range.

The IOC can definitely invest in their own danged facilities, instead of bankrupting local governments every 2 years and then skipping town for a generation.