I would strongly recommend ebb & flow, its low-maintenance and almost foolproof for beginners (such as myself).

American Hydro makes a 3'x3' EconoTray system that I'm using in one room right now and I love it. I find my 4'x4' table hard to get to the back of, so the one foot difference really matters when it comes to ease of maintenance/every day tasks.

With a 6'x9' room you could do two 4'x'4' trays or (if you're feeling really ambitious) four 3'x3' trays. In the end it's up to you to decide how big an operation you're trying to start.