I've used sheets for slipcovers--they work quite well. I would recommend that you get a book from the library on how to make slipcovers. I personally think that they are a pain in the neck!

Annie

I made a slip cover for a sleeper sofa in my basement family room. I used a medium weight denim, but I needed something that would wear well and I didn't want to have to do it again for a long time. Previous poster is right, get a book that explains the basics. I would cut one side and make duplicate for opposite side when it was right. Pin it together wrong side up then sew a section at a time.Is time consuming and may not be perfect. I did the cushions separately (used old covers as a pattern for new covers) so and replaced the worn out foam, foam is not cheap! It took me atleast 25 hours, maybe 35, but mine may be more complicated than what you are trying... alot of patience is needed.

I used denim to make a slipcover for a couch once. It wore well and wasn't bad to work with, but I think Izzie puts her finger on it concerning time--this is NOT a quick fix, it's an economical fix--so be sure to take your time. Poorly fitting slipcovers look bad and are annoying to say the least. And be aware that leather doesn't cover well; it's slick and gives a whole new meaning to the term "slip cover." Plan to readjust them almost every time you use the chairs.

Annie

Maybe you can find some ready made slipcovers at places like Anna's Linens.May be cheaper in the long run,when you factor in buying all the supplies you'll need,fabric,etc and your TIME.Something to think about,before you jump in with both feet.
Kathi