I love them both -- the pastels and contrast in the log cabin are really nice. The bargello really pops.
I just went to a craft fair and the Christmas table runners were flying out of the gals booth and they were not as finely pieced, and they were tied for about the same price. Your log cabin in Christmas colors (or Hannaka blues) would be stunning.
I would say that the table toppers could vary from 21" (for the smaller tables -- both round and square) to about 27" for the larger ones. Folks with smaller square or rectangular tables like to set them on the diagonal without filling the table.