Many of the characters tell you what their plans are at some point in the game, but they never get ending slides to remind you. Letho says that he is going east over the Blue Mountains to start a new life. Roche and Ves go to Vizima to rebuild Temeria (if they survive)- Roche tells Geralt to visit him in Vizima when the war ends. Dandelion and Priscilla presumably settle down to run the Chameleon, though I could see them selling it and returning to Priscilla's native Kovir if Novigrad keeps getting worse. Zoltan says at one point that if he could clear he debts he would "sod off to Poviss." I would expect him to move north as soon as he could to escape the persecutions in Novigrad.
As for other characters, Keira and Lambert (assuming they survive) ride off together, I think east to the Blue Mountains. Eskel says he is going to Lormark (the Kaedweni name for the Pontar Valley where Chapter 2 of Witcher 2 occurred).
Yennefer mentions several possible destinations for where she would want to travel, including Poviss in the north. The city of Aedd Gynvael from the Shard of Ice story is somewhere in the north (Poviss, Hengfors, or something like that), so that would be familiar territory for her. She likes city life, so she would presumably look for a neutral city free of Redanians.
No matter what Triss is going to Kovir to lead the mages and advise King Tancred... or to build a magically-governed Empire of the North like the Lodge originally planned....
) But we know the mothers loves their child eveytime. And Yen worries about her daughter's future. Ciri doesn't want protective angel, she want to be freedom girl