You don't get a choice. You may be assigned to the 75 and go to HI for a long time. You might get the AB or you might get the 80. You could just as easily be stuck out west or stuck out east. There is no way to know beforehand, and the openings change constantly. A base can go through a huge growth spurt, then not have any openings for a very long time and you will be unable to get into that base. You are rolling the dice.