What kind of draperies are you making,pinch pleated,tab tops etc?? I allow 1 1/2 to double the width of the window for fullness.Since your windows are only 36" wide,if you have 2 panels of 54"wide fabric there,that is going to be awfully full,or are you going to cut the width of the fabric down?? Am i making sense??
Kathi

13 yards should be enough for the draperies. I would make each panel one width regardless of the style. Anything else will look skimpy, so 3 yards per panel is 12 yards and it's always a good idea to get an extra yard. Can't give yardage for the valance since you didn't say what style (what kind of heading) you're making. Is the bench cushion a loose cushion with boxing strips or are you just recovering with staples?

Yes Kathy your questions made sense. I am going to use one full width of fabric for each panel.

Drapes are going to be rod pockets on a simple metal rod. Valance will be the same - rod pocket.

Bench cushion is a loose cushion.

OK, I come up with 2 yards for the valance and I'd go with 2 1/2 yards for the cushion (if you're adding self welt), so 13 yards, 2 yards and 2 1/2 yards, total 17 1/2 yards and I'd probably round up to 18 yards (or 17 if you're not adding piping to the cushion).