I believe the choice of at least some of the locations will hinge on whether or not they stick to decade-pertinent themes and film style(s), a la Lucas.
If they do, and chose the 60s as the time setting, it's almost inevitable that at least part of the action will be in the U.S. and/or U.K. (hippies, Beatles etc.).
If they add a spy angle to the story, then add USSR, China or Berlin to the list of likely locations.
If they eschew those time-related references (my favorite scenario), then they have a lot more options and can go for remote, exotic locations, along the lines of what's been suggested upthread.