I like the "feed them and they will come" plan submitted! I also had some luck getting attendance up by teaming with the parent's association. They would provide an ice cream social which was always a big draw. In addition, I also worked with our music teacher, who staged a mini concert, which was a reprise of the previous spring concert, and that brought in those families and students. Granted, this was in an elementary school, which by its nature has more student and parent involvement, but middle school isn't that removed from elementary, so it could work. Besides, who doesn't like free ice cream and a concert?
As to displaying work with limited space, try the ceilings. I had a large elementary school with equally limited wall space, so I devised a system of hanging work from the ceilings. Basically, I prepared display boards with color on both sides, usually with fomeboard in between, but not always. I would then mount artwork on both sides, so when hung from the ceiling, you could see artwork coming and going down the hall. I made the boards out of colored poster board, glued either to the foam or to each other. Pop a couple of holes on the top of the board and hang them in some fashion. Very colorful and very attention- getting. Once you fill your corridors with hanging art, it will gin up excitement with the students and make them more likely to show it off to their parents and friends.