Start with a relaxed breakfast on Mall Road; both Wake & Bake (continental pastries) and Indian Coffee House (old-school masala dosa and filter coffee) serve from ~8:00am and give a feel for Shimla life.
Have an early breakfast and start the Shimla → Manali drive (approx 7–9 hours by road depending on traffic and stops); leaving early avoids evening traffic and gives daylight mountain views.
Solang Valley activities (ropeway/cable car, zorbing, paragliding) usually operate ~9:00am–5:30pm; choose one activity like paragliding (weather-dependent) or the ropeway for valley views.
Short drive to Manikaran (approx 10–15 mins) to visit the gurudwara and hot springs; the gurudwara complex is open 24 hours and the langar provides free meals.
Start very early from Kasol to reach Sissu — you must return via Manali and continue toward Rohtang/Keylong; travel time can be 4–7 hours depending on road and pass conditions.
Before heading beyond Manali, confirm Rohtang/Atal Tunnel and local road status with authorities; Atal Tunnel (seasonally open) and Rohtang may have restrictions in winter or sudden closures.