The smaller chair is too small and gets lost in the corner, Are you doing the reupholster yourself? If not it may be better to donate both and purchase a nice new chair. Materials and labor for reupholstering chairs can get very expensive.

I agree with Jamie. Reupholstering is very expensive or if you do it yourself it can be quite a nightmare (trust me)! My vote would be to invest in a new chair. It's also a great place to add some interesting pattern or pop of color. You could do something like this: