I don't think there is any number that is too many...I hang quilts all over my house...larger quilts, wallhanging size, tablerunners, a quilt rack with many quilts draped on it, and a cabinet full of quilts that are out...I do rotate seasonally what quilts I have on display...that is the fun of it...to see different quilts. I don't think I have too many...as long as they aren't totally covering the walls...well...maybe that wouldn't be too many either if you were happy with how it looks.
Enjoy all your quilts!