Hammerfell seems like the only real option. Although a Valenwood/Elsweyr/Summerset Isle trio would be awesome, or a re-release of Morrowind

Here is a map of Tamriel to use for reference
http://5493-planetmc.voxcdn.com/file...sfd_581340.jpg

They might just bundle in High Rock with Hammerfell if thats what they choose to do