Leather or fabric is usually used as these are more comfortable for people sitting on a chair. Vinyl, being a plastic,,doesn't allow breathability so it can get sweaty for a sitter. Also not considered a high or medium end material. Although for fun factor it can work.

Usually people choose vinyl for durability. If this is the case there are very durable leathers out there and in a wide range of colors that can give you both the comfort of leather and the durability of vinyl. The Spinneybeck "Acqua" Collection is a great example of this:
http://www.spinneybeck.com/colorbook/ProductColorList.aspx#&&SearchTerm=acqua

The chairs are great pieces. I would hate to see them "cheapened" but the use of vinyl. You can get a bit of fun with upholstry material in many many different prints. When I think of vinyl, I think of the split cushions sitting in an out-dated doctor's office.

Vinyl is an update, but not in the positive sense.

NOOOOOOOOOOOO!! to vinyl! If you cannot use leather, get nice fabric.

I have two words for you: SWEATY, ASS

microfibre! Easy to keep clean!

one word..cheetah print!

I call for a recount.

Since you are using these in a monochromatic space I would go for something with a wow factor, but if the choice is leather or vinyl , leather it is.

Ignore all the naysayers about vinyl. As even with leather, there are cheap versions out there. Company loves our "beautiful leather" barstools...that are vinyl.

Vinyl often looks cheap, but it has nothing to do with color. If your room is beige, beige vinyl won't make the room less monochromatic. Pink suede would be as colorful as the same shade of pink vinyl, more comfortable and more elegant.

The chairs are really beautiful and warrant something special like a beautiful natural linen...I think vinyl would be a mistake.

Vinyl may look similar but, as others have pointed out, not conducive to sitting for a while. I don't think its worth the little savings difference and you won't get the softness of the suede. But if you would prefer something other that leather, try a woven tapestry with a muted color palette. I have done similar chairs which have lasted for decades with few signs of wear with a good quality fabric though that could cost as much as the leather. Are the seat cushions original to the chairs? They seem a bit more casual than the chairs themselves, maybe added later for more comfort as these chairs were made for occasional use (company) rather than for everyday comfort.

I love those chairs, very classic. How about adding bolster / lumbar pillows in an unexpected fabric or color?

Looking at the body of these chairs I wouldn't use vinyl only real leather or fabric .

I would opt for true leather or a fabric. Leather ages beautifully--but you must understand that and appreciate the aging look--or go with fabric. If wear is an issue, select a fabric with a high rub-test rating--there are beautiful textiles that have extraordinary durability.

As for the specific pattern and design, this should be determined as part of the whole--not as a one-off suggestion. It's a process!

Do the backs of the chairs in leather. The remaining parts would be Velvet (horsehair style).
Use leather welting which matches the outside backs to trim the seat cushions.

PS The leather can be a shade darker than the solid Velvet.

(*keeps fingers crossed*) Please no vinyl, please no vinyl, pease save the chairs from the viny fate! Here is something with such a vivacious palette! http://st.houzz.com/fimgs/d2210fbb0e9eda57_0349-w106-h106-b0-p0--eclectic-family-room.jpg
By some reason the immage does not want to appear...
Eclectic Family Room by Santa Ana Interior Designers & Decorators Darci Goodman DesignEclectic Family Room by Santa Ana Interior Designers & Decorators Darci Goodman Design

First of all the chairs look like they need to be re-stuffed before they are re-upholstered. Please do that when you do the re-upholstering. Secondly, there are many vinyls in todays market that simply do not look like vinyl. In particular, I love the new patent leathers which are very chique. The other consideration is what these chairs are being used for. If these are host and hostess dining chairs the vinyls are more practical to wipe for food spills. The other choice could be one of the poly suedes which are washable and very handsome. Good Luck.

Beautiful Chairs!!!! And PLEASE no vinyl!!!! Can't afford suede, microfiber would work or a wonderful subtle upholstery fabric and those seat cushions need help...

Dear God...stay away from vinyl.

Those chairs look like they can go many ways. If it is ease to keep clean that you are worried about, check out sunbrella indoor outdoor use of fabrics. The vinyl will not work well with the cushions unless you put in vents. Vinyl is not comfortable for sitting on for very long. Your upholsterer can eliminate the nail heads and provide a nice welting. Lots of potential but I don't think the even the metallic vinyls that they are using will catch on just for the reason that they are not that comfy.

No vinyl. There are some very beautiful natural fabrics available. Believe me, if you use vinyl you'll regret it. Ask me how I know ! ;)

The chairs need restuffing and I would go with fabric for a more contemporary look. You could even do the back one fabric and the seat a complimentary fabric.