Having been to Bergama, I can tell you this is an amazing place. An imposing temple stands at the top of a 1200 meter or so mountain. Winds blow at the top that will make you feel you will be blown into the valley below. I remember my wife driving in the valley below, and before we had even entered the town, I looked up, saw the Temple, and said - I know exactly where we are going. It is a powerful place, and the presence of "the gods" is felt from miles away as one looks to the top of that mountain
That said, the reference in Revelation as to its position as "Satan's seat" is not that he has a chair there, but rather that it was a "capital" of sorts in Satan's empire. It was a place of power in Greek theology (and remember, Turkey was Greek at the time!) In the same way that Washington, DC is the "seat" of power in the United States, Bergama was the center of power for a particular belief system that emphasized the power of the gods to grant healing.
The Greek god Asclepius in particular drew followers from all over to experience healing. The fact that this pagan influence was so strong would likely have led John the Revelator to say something to the effect of "Satan is very strong here," as evidenced by the deep pagan influences against which Christianity would place itself.
All this said, this does not address the question of Satan's abode. As a created being, Satan must, by definition, have a physical presence. Unlike God who is omnipresent, Satan is a finite being. As such, he has a place. When in Job, for instance, he confronts God, it says specifically that he had returned from walking the earth, and seems to indicate that there was a place in which he could come face to face with the presence of God. Whether the earth was his home or merely on his intinerary is unclear from Scripture.
One can argue whether it is he who is cast down from heaven in Revelation 12, 18, and other places, or whether he is embodied in the "AntiChrist" or not, but this much is sure: At some point, I'll be able to pinpoint his exact location. It will be in a lake of fire where he'll spend the rest of eternity. I'd rather not have any closer understanding of his geography than that. :)