Esslingen's main draw is its intact medieval townscape — most of what's worth seeing is within easy walking distance of the Marktplatz. Allow at least half a day; more if you plan to take in the castle, the vineyards, and a tasting at the Kessler cellars.
The Marktplatz is the obvious starting point, with the Altes Rathaus, Stadtkirche St Dionys, and Frauenkirche all within a few steps of each other. From here, a climb through the vineyards leads up to Burg Esslingen, with progressively better views of the Neckar valley as you ascend. The medieval town walls are worth exploring on foot, and the Innere Brücke and Neckar waterfront make a pleasant afternoon wander.
The Württembergische Landesbühne stages drama and opera throughout the season, and the Stadtmuseum fills any gaps in understanding the town's history. For wine, Kessler Sekt is the obvious stop for a tour and tasting. In November and December, the Mittelalter- und Weihnachtsmarkt transforms the old town into one of the finest Christmas markets in the region.