Thessaloniki is a very lively town: It's fun to spend time here simply wandering and browsing through the shops and galleries along Tsimiski, Aristotelous, Ayias Sofias, and pedestrianized Dimitriou Gounari streets. Don't miss the enormous neon high heel at the Karidas Shoe Store on the Via Egnatia (or the ruined Turkish bath across from the shoe store). In the evening, if you want to see young Thessalonians working at relaxing, take in some of the bars on Zefxidos Street, in central Aristotelous Square, or at the Mylos complex on Andreou Georgou.
When you've had your fill of city pleasures, you may want to head out of Thessaloniki to see some of the sites associated with Philip and Alexander, such as Vergina, Dion, or Pella. If you'd like to avoid a lot of driving, sign up for one of the efficient day trips that take in these sites. If you plan to see the sites by car, consider exploring them on your way out of town rather than as a day trip, in order to avoid fighting your way in and out of Thessaloniki's fierce traffic.