Visit the hilltop Kamakhya Temple (typically open 5:00am–6:00pm) — an important tantric Shakti site with great city/Brahmaputra views; expect queues at peak times.
Enjoy an Assamese thali and local fish/vegetarian specialities — Khorikaa is known for regional dishes and gives a good introduction to local flavours.
Drive up to Shillong Peak for panoramic views then stop at Elephant Falls; both are open during daylight hours and are must-sees for first-time visitors.
Return to Guwahati early (road transfer or short airport hop from Shillong) to catch a morning flight to Agartala; flights typically ~1 hour. Have breakfast en route or at the airport.
Eat at stalls and small restaurants in Ima Market to try Manipuri specialities like singju (salad) and seasonal fish dishes — market open most of the day.
Travel early to Itanagar; arrival may require changing flights at Guwahati — ensure permits/ILP are in order for Arunachal. Have a light breakfast at the airport.
Begin the long transfer to Bagdogra/Siliguri by flight (Itanagar→Guwahati→Bagdogra) or overland where possible; final stretch is a 3–4 hour drive from Bagdogra to Darjeeling — expect a full afternoon and evening in transit.
Check into your Darjeeling hotel and enjoy dinner at a well-known hill-station café like Glenary's or a local restaurant — savour tea-house ambience and mountain air.