One of the initial concepts for the show: setting the base on Bajor not on a space station and the lead character being Dr. Julian Amores not the Starfleet commanding officer, who would've been Lt. Ro Laren.
According to The Making Of Deep Space Nine book, this concept didn't last to long due to budgetary considerations. A lot of location shooting would've been needed on a weekly basis and the constructing of an outdoor set depicting the nearby encampment.
I've always thought that this concept would've completely subverted the Trek format in a good way. One, it would've been set planetside and not in space. Two, the lead character was not the traditional starship/starbase captain. Hell it would've also prevented the lame B5 v. DS9 arguments.