How about soft blue velvet? I think it would look beautiful with the wood.

http://www.notyourgoddess.blogspot.com/

What about a gray velvet or mohair?

The lighting is yellowish in your chair photo, and it's hard to know what would look good in the lighting of your home, but...

This fabric has a pretty color. I think the "sea mist" would go well with a dark wood color. Apparently, it's stain resistant (I don't know much about home decor fabric or this particular brand): http://www.joann.com/joann/catalog/productdetail.jsp?CATID=cat2143&PRODID=xprd881530

This has a subtle design that might work with the tufting: http://www.joann.com/joann/catalog/productdetail.jsp?pageName=&PRODID=xprd944109

Maybe a nice brown that shows off the wood?

My opinion is that you should go with gray, as suggested above, OR with something really bright, like orange, turquoise, or red. Determine what would best complement the rest of your decor then be BOLD if you can!

Yes, luvcolour is right on. Mohair of course. The synthetic Mohair (vs. wool) is half the price, very durable and quite attractive.

Please know that you don't have to retain the diamond tufting with the new upholstery.

Whatever you choose - if you retain the tufting, make certain it's a solid, large-scale floral or a paisley...
...no stripes, plaids, geometrics or ditzy designs.

Bepsf, I thought the rule was if you have deep tufting your pattern had to be very small. Wouldn't the tufting warp the pattern beyond recognition if it was large?

I say pick whatever color you like and goes well in the room.

I once covered a "granny rocker" in a leopard print. My rocker was an Eastlake style. I loved the juxtaposition of a very un-granny-like pattern with the antique rocker.

"The synthetic Mohair (vs. wool) is half the price, very durable and quite attractive."

What the heck is synthetic Mohair? No such thing and mohair is not half the price of wool.

I would do a classic boucle wool nubby texture
like this one- http://www.knoll.com/products/textileproduct.jsp?prod_id=162

or a Leopard print would be fun and classic-

check this out for inspiration-Leopard is in again and it will always be in just that one piece
http://thepeakofchic.blogspot.com/

I love the Les Must Die Cartier book cover in Leopard print

Perhaps a linen?

Becca

http://thedivinechaircompany.com has some great ideas.

I really think it would help to have some context here - a pic of your current home would be great! The first thing that came to mind was a dusky blue and would nicely complement the aged wood. You could punch up the impact of the blue with some bright pillows or blanket, or make the chair blend more if left alone.

If you have a very bright home, I thinks some bright chartreuse or leopard print would be fun. Or a fuschia velvet - bright! - would be fun.