Here in SW Florida, the roots of the wild bermuda grass growing over my drain field has clogged the perforated pipe several times... I am considering just removing all the grass and putting gravel of some sort over the whole area and using potted plants as landscape material... essentually creating a patio feel... the question is, should I put down a weed barrier (thick plastic, landscape fabric etc. ) under the gravel or will that interfere with the function of the drain field?

Well the water would drain downward, so covering the area wouldn't matter, but you would be creating an environment that is anaerobic instead of aerobic, and anaerobic bacteria are like those horrible zombies that cover stuff that's been in your refrigerator too long or give you food poisoning. Cause things like polio and meningitis and claustridia. Better to forget it