Hi there! In my opinion, I'll pick a lighter solid color fabric.

I'm no help...I think either in a solid would work. But keep in mind, that lighter fabrics will highlight wear and stains faster.

why does it have to be taupe or gray ? I don't think either one work all that well w/that mahogany tone. what else is going in the room?

Like what you have, too. Wouldn't remove/destroy these seats unless the seats are stained or worn or otherwise damaged.

Like the separate cover idea but not "white", probably not linen and not w/scalloped or lace edges dangling down.

You might choose a fabric that you could use to to create a cover with four ties or straps w/velcro to attach to the four leg of the chair.

A solid color will show stains more but if you're going to choose a solid color, consider finding a solid color you like from within the window treatment you have in the dining room or adjoining room.

I like the brownish/gold color within the current pattern.

I like what you have also, but could also see the seats with a colorful chinoiserie fabric.

chinoiserie fabric