This is something I thought about when I played GC and FH - the ability to choose to have your hatches and such open for a better field of view, or to shut everything so that you have a very limited field of vision, but your crew is harder to kill.
For example, in GC, when you sat in an AT-ST seat, you had the open hatch and a computer screen to look out through. I imagine that if you removed the 'Plexiglas' and gave the player the ability to shut the hatch when under fire, it'd be a nice feature. I'd also like it if hatches were open when there were people in the opening, so grenades and such could actually enter the vehicle and kill the crew, but closed when there were no one at them.
To accomplish this, fully model the interior of the AT-ST, and implement the driver's position, a secondary position, two passenger positions, and the hatch position. When exiting either, you end up on the ground or perhaps on top of the walker.
I think it'd be interesting to be in an AT-ST and balance safety for vision. Do you keep your hatches open and leave a guy topside, or do you close everything down and play it safe, knowing it'll reduce your ability to detect enemies? Surely this could be implemented for other vehicles, too.