Both the Shimla and Manali routes offer unique experiences while traveling from Delhi to Spiti. The Shimla route is longer but open all year and safer for gradual acclimatization. The Manali route is shorter and more dramatic but seasonal and challenging. Manali to Kaza includes high-altitude passes and is open only from June to October. If you’re a first-timer, choose the Shimla route. Experienced drivers and adventure seekers may prefer the thrill of Manali’s route.