It’s obvious that all of them are in Tar Valon at the beginning of the season. The Mat clip and the trailer feature several moments showing all the main characters in Tar Valon.
In the books, the girls did go back to the Tower to continue their training and inform the Amyrlin of the events in Falme. I can’t think of any reason they wouldn’t do that in the show, except to stay and protect Rand now that he’s been proclaimed the Dragon Reborn. However, that can be accomplished by Rand going with them.
Of the remaining characters, Mat and Perrin would want to stay with Rand, as would the maidens and Loial. Obviously, Moiraine and Lan also stay with Rand. So the question is: how did Moiraine convince Rand to go to Tar Valon? There are several reasons why he can’t stay in Falme because of the public proclamation. The Forsaken are out there, Rand doesn’t have an army, he doesn’t have Callandor, and he is nowhere near the channeler he is in the books. If a channeler decides to attack them, their only defense right now is Moiraine. So, if he stays in Falme as the Dragon Reborn, he will be captured by the Aes Sedai, and that’s assuming the Forsaken don’t get him first. He can’t just relax as the ruler of Falme, like he did in Tear in the books. At this point in the show, he has to hide from the Aes Sedai and the Forsaken.
How will he hide from the Aes Sedai in Tar Valon? From the sneak peek, it seems that Moiraine and Siuan have reconciled. All of the Aes Sedai who know Rand is the Dragon Reborn are part of Moiraine and Siuan’s circle. So, it could be like season 1, where he blends with the crowd in Tar Valon and isn’t really relevant to the other Aes Sedai.