Since the 6" figures feel a little less like toys and a little more like display pieces, I would be in favor of "environments" more than vehicles. Seeing the 6" scale TIE Fighter reinforces my belief that these are going to be really hard to interact with as toys, and potentially really hard to display.
The only vehicle that I would love to see in this scale is a landspeeder, but if they do that they've got to make a C-3PO.
My quick thoughts on "environments":
- Jabba's Sail Barge (or palace) - would be great to have somewhere to display a bunch of the figures we have that fit this scene
- Death Star - maybe around the detention center, but you'll need to make a "Death Squad Commander"
- Hoth Base - I need a place for my Tuantaun and Wampa
- Mos Eisley Cantina - I would love to see a whole wave of cantina patrons (Hammerhead please) to go along with the release of this set
It would be cool if they made these environments with a pack in figure that we wouldn't normally see - e.g. Yakface with a Jabba's Sail Barge.