I love Thessaloniki, really, but driving around and parking is a nightmare! The only way to avoid it is to arrive in the evening, after the shops close and park in strategic locations close to the center. Alternatively, you can stop in Kalamaria, on the sea and move around by public transport or use the free RV area, 18km in the direction of Chalkidiki.
I have just returned from Thessaloniki, where for ten days I have been following the international documentary festival. An event that for years I do not miss and an opportunity to enjoy the city in spring version combined with an excellent selection of films and other events. This year I also managed to break my previous record and seeing 36 films, one better than the other!
For years now we do the route Athens Thessaloniki without taking the highway. On one hand the cost of tolls that for an RV exceeds
50 70 € for 500 km. On the other, the fact that the alternative routes are more interesting and even if they require a few more hours of driving, the mileage does not increase by much, in the worst case we are talking about 50km more.