Since my own preferences are for gaming in the Spinward Marches, I'd really like to see Zhodani and Droyne. Especially since I want to update one of my old CT characters: a Zhodani noble built using the SORAG book
(For all you young'uns out there, SORAG was the name given to a Zhodani commando type organization. As a noble, a character would automatically have psi abilities, the character prior history would give plenty of opportunities to improve psionics. And of course, as a commando type, there are all sorts of nifty combat related skills to gain. My copy is deeply buried, I mean archived, if I even still have it. Wasn't it put out by FASA?)
On the other hand, gaming on the other sid of the Imperium would allow the chance for K'kree and Hivers. I've always wanted a chance to torment K'kree with the smell of meat on my breath. (Keep some jerky handy just for them!) Hivers, on the other hand, are just too neat... I always hated the fact that they were several sectors distant from the Spinward Marches.
On a (slightly) related topic, when might we hope to see miniatures? The Martian Metals 15mm stuff was nice for Striker, but not much good for role-playing.