I did a campaign on Govon ( Star Crown Empire ) for the same reasons as you ( A GM was already busy making us crawl over all Jaiman ).
There's a bit more than Palia ( as there's a whole book about it ), but there's really not much, you have to invent a lot of things, but there's an existing framework that is more important than a few lines in the Master Atlas.
I also toyed with parts of Thuul ( the south ) while the GM above played with Gethrya and the Jan ( so northern Thuul ).
All in all there's not many places beside Jaiman and Emer that are described with more than a few lines in the Master Atlases : Gethrya & The Jan ( NW Thuul ), Govon ( Star Crown Empire ), Islands of the Oracle and a few other places here and there ( Magic Isle, Tales of the Loremasters, ...)
And you have Folenn, but the description is clearly oriented towards skirmish gaming.
That's more or less all for the officially published products ( canon or not )
If you were lucky to be part of the SW mailing list around Y2K you might have seen some descriptions about the Shinh Archipelago off the Emer Coast, some stuff about centaurs in Muliria, and a few other stuff.
But some of it has been voided by the Master Atlas IV.
*whine about the Punkari*
There's also some informations here and there on the net, but it tends to be mostly Jaiman or Emer centered.