I'm guessing you mean "holiday" in the British sense, which Americans call "vacations." (We reserve the word "holiday" for religious holy days and national days of celebration and commemoration.)
Assuming I got that right, it would have to be my 3-week pilgrimage to India called In the Footsteps of the Buddha. Traveling with 35 North American Buddhists, including teachers from 3 different Buddhist traditions, we saw where the Buddha was born, where he was raised, where he attained enlightenment, many places he taught, and were he died, as well as the later monastery, Nalanda, where many great Buddhist works were written.
Of course, I loved the people and the food.
Also, flying down from Katmandu at 11,000 feet (over 2 miles up) in the foothills of the Himalayas to the forests, fields and rivers of the vast plain north of the Ganges at 400 feet above sea level was - awesome!