My daughter used to be a Candy Striper at a local Long Term Care facility. There they called the adult bibs, Dinner Jackets and they were nicely designed, some for women, some for men and some basic ones.
I never handled them, but they were not bulky and did have a nice faux front with buttons.
How many are you making and will they be washed in an industrial or home laundry? My first thought was PUL or Babyville tm diaper cover fabric. If you have a medical supply house nearby, you could check into waterproof mattress pads. They are designed to go through high heat laundry and should hold up.