The vineyards above Sion produce some of Switzerland's most distinctive wines, and the old town has several good tasting rooms and wine bars where you can work through the local varieties. Switzerland exports almost no wine — what's made here stays here, which means you're drinking wines most of the world never gets to try.
Fendant (Chasselas) is the classic Valaisian white: dry, light, and mineral, the natural companion to raclette and fondue. Johannisberg (Silvaner) is rounder and slightly floral. Among reds, Cornalin is the most interesting — a variety nearly unique to Valais, with cherry and spice notes that differ noticeably from anything made in neighbouring cantons. Humagne Rouge has a wilder, earthier character. Any of the serious tasting rooms in the old town will guide you through them.
For a more immersive experience, several domaines on the hillside above the city offer cellar visits and tastings, particularly during the autumn harvest season. The drive or walk through the terraced vineyards with Tourbillon and Valère on the hill above is one of the more beautiful wine-country experiences in Switzerland.