Why does the Torah deem it necessary to list all Yisrael's journeys in the desert?
Rashi #1 (citing R. Moshe a'Darshan) and Ramban: To teach us Hashem's kindness - since, even though He decreed that He would move them around in the desert, we should not think that He moved them incessantly from place to place without respite throughout the forty years. We see here that they only made forty-two journeys. Deduct fourteen that they made during the first year 1 - before the decree was issued, and eight, which occurred after the death of Aharon in the fortieth year, 2 after the decree had been rescinded, and it transpires that, during the thirty-eight years that the decree was in place, they only traveled twenty journeys.
Rashi #2 (citing Midrash Tanchuma): It can be compared to a king who took his sick son on a long journey to obtain a cure, and who, on the return journey, began to recall the stops that they made on the way out - 'Here we slept!' Here we suffered from the cold!' Here you had a head-ache!' 3
Ramban #2 (citing the Moreh Nevuchim): To prevent a situation where people think that Yisrael survived forty years in the desert by living in the outskirts, near inhabited country, 4 within range of grazing-grounds for their cattle or in areas where vegetation and plants were available to provide them with food. Therefore the Torah describes their itinerary, that we should realize that they traveled far from inhabited country, where no food was available, 5 places where, under normal circumstances, nobody could possibly survive. 6
Ramban #3: It was a Divine Command to write down all the places that they passed, for the above reasons or for some unknown reason that Hashem did not reveal.
Rashbam: The Torah repeats their itinerary, to teach the names of the places where they encamped.
Seforno: It is to teach the merits of Yisrael, how they followed Hashem in the desert, a place where nothing grows, in a way that rendered them worthy to enter Eretz Yisrael.
Targum Yonasan: To make us aware of the miracles 7 that Hashem performed wit Yisrael.
Rashi: From Hor ha'Har to Arvos Mo'av.
A sign of love and intimacy.
Ramban (Ibid.): In the way that nomadic tribes survive nowadays in desert areas.
Ramban (Ibid.): And they survived miraculously on Manna.