I will suggest only less or non commercial treks. Because famous trekking routes will be crowded and you will loose the sense of thrill and adventure. Ranking easier to tough
Triund Dharamshala:
2 days – best for beginners and one of the most scenic treks
Kareri lake Kangra Dharamshala:
2 days easy to moderate ,its very different trek from other treks as you will find snow water spring accompanying you all the time.
Lambri Trek jalori pass: 3 Days– recommended-Easy
This trek as the best 360 view of himalayas
Brighu lake Manali: 3 days – recommended
Indrahar pass Dharamshala:3 days moderate to difficult
Shrikhand Mahadev if you want to Trek high altitude in less time ,18000 ft high
You can call for free help and suggestions at 8750807666,we can help you connect with local guides all over himachal.