Here's a suggested tour package for a 3-night, 4-day trip from Rajkot to Dwarka, Somnath, and Diu, returning to Rajkot:

Day 1: Rajkot to Dwarka
- Start your journey from Rajkot in the morning and drive to Dwarka, which is approximately 225 kilometers away. It usually takes around 4-5 hours to reach by road.
- Upon reaching Dwarka, check into your hotel and freshen up.
- Visit the revered Dwarkadhish Temple, dedicated to Lord Krishna. Explore the temple complex and take part in the evening aarti (prayer ceremony).
- Spend the rest of the evening exploring the local markets and enjoying the beautiful coastal views.
- Overnight stay in Dwarka.

Day 2: Dwarka to Somnath
- After breakfast, check out from your hotel and depart for Somnath, which is around 240 kilometers from Dwarka. The journey takes approximately 4-5 hours.
- En route, you can visit the Nageshwar Jyotirlinga Temple, one of the twelve Jyotirlingas (shrines) dedicated to Lord Shiva.
- Upon reaching Somnath, check into your hotel and relax for a while.
- In the evening, visit the famous Somnath Temple, one of the twelve Jyotirlingas and a significant pilgrimage site for Hindus.
- Enjoy the mesmerizing sunset at the Somnath beach.
- Overnight stay in Somnath.

Day 3: Somnath to Diu
- After breakfast, check out from your hotel and proceed to Diu, located approximately 90 kilometers from Somnath. The drive takes around 2 hours.
- Upon arrival in Diu, check into your hotel and unwind.
- Explore the serene beaches of Diu, such as Nagoa Beach and Ghoghla Beach, where you can relax, swim, or indulge in water sports activities.
- Visit popular tourist attractions in Diu, including Diu Fort, St. Paul's Church, and Diu Museum.
- In the evening, witness the beautiful sunset at the Sunset Point.
- Overnight stay in Diu.

Day 4: Diu to Rajkot
- After breakfast, check out from your hotel and begin your journey back to Rajkot, which is approximately 210 kilometers away. The drive takes around 4-5 hours.
- En route, you can visit the famous Gir National Park, renowned for its Asiatic lions. Please note that this will require additional time and planning.
- Reach Rajkot by late afternoon or evening, concluding your tour.

Please note that this is a suggested itinerary, and you can customize it according to your preferences.