At the beginning of A New Hope, Princess Leia has just received the stolen plans for the Death Star. Yet rather than take these plans directly to the Rebel base on Yavin IV, she first stops off to pick up Obi-Wan Kenobi. From dialogue in the movie we also learn that, after picking-up Kenobi, she is supposed to go to Alderaan to meet-up with her adoptive father Bail Organa. Presumably then everybody would proceed to Yavin IV from there.
If we take into account the events of Rogue One, Bail Organa told Leia (offscreen) to go to Tatooine to get Kenobi, however this was done before Leia ended-up with the Death Star plans. You would have thought, given the change in circumstances, she would determine that it's more important to get the plans to Rebel command than stop off at Tatooine first. Especially as, at this point, she would have known about the Death Star's destruction of Jedha.
Have I missed any movie dialogue that describes or implies why Leia thought it more important to go to Tatooine, then on to Alderaan, before taking the Death Star plans to Yavin IV? Or is there anything in any of the books or supplementary material to explain it?
Of course if she had gone straight to Yavin IV with the plans then the original movie would have been very different!